If you need emergency services, they can be called to come to you, but you're far better off going to them if at all possible summoning help is a slow process; fire trucks and ambulances may need gas before they can be sent out, and nobody knows the phone number for these agencies anyway as there is no 911 or 999 service. Taxi and moto-taxi drivers typically know the police station which is just west down the street from the main gate of the market, the hospital a landmark unto itself, probably .5 km southwest from the market and the fire station probably 2km south of the market. If you have serious injuries, most taxi drivers and private drivers are pretty charitable about getting you to help and securing payment after the fact, if at all.
Maradi is a highly safe city inhabited by friendly, helpful people and you can reasonably expect to get through your stay without experiencing anything worse than a scam or a petty theft. In particular, you will find Maradi to be a pleasant break from the tourist-targeting con artists that haunt the hotels and markets in places like Niamey and Agadez. Still, be smart: It is a city, and all kinds of people live there. Being an obvious foreigner assuming you are makes you less of a target than you are in several other Nigerien cities, but don't worsen your odds by wandering around alone, drunk, and conspicuously wealthy. Hide the 10,000 franc notes or better, change them for denominations actually used on the street, if you can, keep your money in two or three places on your person, and be respectful of local culture.
Foreigners get flirted with all the time, and on-the-spot marriage proposals are fairly common and probably harmless. You should be polite and friendly and you may reasonably assume that the proposal is largely humorous or facetious in its intent , but don't do things to encourage it like dressing immodestly men or women, or giving out your cell phone number or hotel room to people you just met on the street and they will ask. The author has never heard of a woman being assaulted in Maradi, but that's a personal experience over two years of living there; don't take it as any kind of fact or assurance and regardless, don't risk becoming the first.
A simmering Tuareg rebellion in the north of the country comes and goes; you can travel all through the south of the country and never know it was happening beyond maybe passing a convoy on the road. The rebellion has been connected to a bomb attack in Maradi, Tahoua, and Niamey in 2008, but that incident was a shocking and isolated incident. Similarly, Al-Qaeda in the Islamic Maghreb AQIM has been active in Niger in recent years. So far, incidents in Niger have almost exclusively occurred in the north and west of the country - there was a failed kidnapping attempt on US embassy workers in Tahoua, and a few tourists, aid workers, and diplomatic staff have been snatched, almost entirely in the Tillaberi region; at least one French hostage was recently killed. Maradi has never, to this author's knowledge, had such an incident. The situation, however, is dynamic, and you should seriously consider contacting your embassy or diplomatic service before arriving to get an update.
The biggest threats to your safety in Maradi are not human in nature. Stings from Maradi scorpions and spiders are not normally lethal, but they are painful, and even in the city center you might find a snake from time to time Nigeriens hate them and will kill them upon finding one. Many of the streets get turned over to wild and semi-wild dogs late at night. The most dangerous animal in the city, however, is without doubt the mosquito. Your guidebook says that Maradi is an arid or semi-arid climate, but the city more than most in Niger is lousy with mosquitoes, and the Falciparium strain of malaria they carry is the most virulant and lethal in the world not to mention less deadly but equally unpleasant illnesses such as dengue fever. During the rainy season June-August in particular, the numbers explode and turn the area into a buzzing, itchy purgatory on earth. Repellent helps, and at the Guest House, at least, your bed should have a mosquito net, but know that malaria is largely responsible for Niger's truly obscene child mortality rate and that several foreign aid workers each year stagger or are carried into local hospitals each year, where they die without ever regaining consciousness. If you're going to visit, follow what your guidebook is already telling you and get on a good malaria pill before you arrive.
It is a good idea to carry medical evacuation medivac coverage as part of your travel insurance.
contact
Internet infrastructure has recently developed in Maradi to the point where cyber cafes have become a reasonable business option, though the connection is often slow typically, they have multiple computers using single connections, so even places advertising a high-speed connection have this problem and very few have generators, so they are at the mercy of Maradi's frequent power failures. Most of the cyber-cafes are around the market: A boy scout-style youth, GARKUWA, runs one a block west of the main gate of the market; there is another one on the market's west edge, and one on the south. The most prominent one is located in the Ecobank building on the market's southeast corner.
Public phones are available throughout the city; typically, they are located in shops with white-and-blue "Cabine Telephonique" signs don't take "cabine" too literally; you're just as likely to find market stalls telephoniques or even coffee tables telephoniques where an attendant charges you by the minute on a largely reliable land-line telephone. You also can occasionally find people who charge you to make calls on their cellular phones, though this is more common in villages.
cope
Maradi can really be a full-blown sensory onslaught, and to a casual traveler there isn't much in the way of escape from it. Worse, it's a grueling ten hours to Niamey and several hours including a border crossing to Kano to a foreign tourist, neither of which are the most relaxing of places themselves, so when you consider the sinking feeling that you're in over your head, you also come to realize how hard it's going to be to get out of Dodge. The best, and truest advice for a traveler to Maradi is that if you are easily overwhelmed or prone to paralyzing culture shock, this is probably not the place to visit.
That said, there is a decently-sized crowd of foreign nationals that calls Maradi home, including missionaries and aid workers from the United States, France, China, Lebanon, New Zealand, Japan, and elsewhere. As a whole, they are exceptionally compassionate, friendly, and welcoming, and some of them have lived full-time in Maradi for 15 or 20 years. If you are in desperate need of help or just a place to hide from it all for a while, you can often bump in to some of these folks in the nicer grocery stores around the market, at the Guest House, or down by the pool. Many of these folks are extremely kind and gracious and are willing to help travelers in need, even if all you need is to hear your native language spoken for a little while.