Depression in mild to moderate dementia patient.

Had to put 95 yo mild to mod dementia mom in nursing home 2 wks for respite while I had hip replaced. She came out not wanting to do even the little she would do before, and now doesn't want to eat or drink anything. Was eating 3 small meals before. Would read mail, newspaper, play solitaire... Now wants nothing but lay around and sleep. Days she wants to die. Suggestions for getting back in track? Mental acuity is same.