If you are travelling in a group, it is worth to check out the guide "Accessible group accommodations in Flanders and Brussels" by Visit Brussels. All new guide (2018) prepared with care and lots of useful information for you and your tribe!
Thuiszorgwinkel is an organization that provides mobility aids and special medical aids for different types of needs. They do not have a shop in Gent but very nearby. It also rents mobility aids and the staff speaks French and English. Their website is only in Flemish so we advise you call the store.
Located right next to the Belfry in the heart of town, the NH is a 4 star hotel with one room with accessible bathroom, roll-in shower and shower seat with foldaway armrests and grab rail. The hotel also has a restaurant.
Located near the E17 motorway and the University Campus, the Holiday Inn Express hotel has one room with adapted bathroom, with roll-in shower and shower seat. Make sure to specify you need the accessible room when booking.