Where can I find affordable assisted living for my mother-in-law with possible dementia?

She is on a very limited fixed income and cannot afford to stay in her residence alone nor should she be left alone for much longer. We are looking for any assistance programs she may qualify for or any agencies that can help us locate appropriate housing. She is resistant to selling her house but cannot maintain it on her own any longer. She has fallen behind on her maintenance bills and is in need of a new residence as soon as possible. She has a potential buyer for her home but cannot consider a sale until she has somewhere to go. Any help we can receive would be greatly appreciated!!