My mom and dad are close to getting an apartment in senior housing. Dad has dementia. Is it wise to have them make a big life change?

It's going to be hard on him to move, but it may be necessary for your mom. Taking care of their house will be hard for her, and the steps will eventually become impossible for him. Wherever she lives with him, she is likely to need help. It would seem that the move now is better than waiting unless he is at the point where he needs a nursing home.
Good luck,
Carol

He is close to going into a nursing home at this point. We are trying to keep him home as long as possible. The senior housing told me if he does, she loses maybe half her income, and would have to leave and go to another senior housing facility. I think its too much for them with all that change, even though nothing has happened yet. I guess I am trying to foresee the future here, but this may happen.
Also a sibling who owns the house is giving me a hard time having mom stay there if dad does go in a NH, so I may just let her stay at my house even though I really do not have the room and figure something out, rather than her be sad and lonely.