physically debilitating alzeimer's

My stepmom was diagnosed with alzheimer's back in the fall of 2001.  She was in her early 60's.  She steadily declined until my dad could no longer take care of her at home in the summer of 2005.  She was not wandering or anything like that, instead, she was becoming totally incapacitated physically.  She would fall frequently, could not dress, bathe, or go to the restroom on her own.  At the time she was heavy, so it was becoming impossible for my father to take care of her.  He is in his 70's.  At that time he put her in a home since he had long term health care for her.  Although her mind was deteriorating rapidly, she still knew that he was "throwing her away" and was quite upset about it.  My father is very dedicated and has visited her every day while she has been in the home, but he ran out of long term health care this month and had to bring her home.  At this point she is totally incapacitated, completely bed-ridden, and basically in a vegetative state.  She does know how to chew food when fed,  drinks from a straw, and mumbles to herself.  She has lost alot of weight, but seems to be doing well otherwise.  I have not been able to find much information on patients with her types of symptoms.  It seems as if alzheimers patients in the advanced stages seem to be quite mobile.  When my stepmom was admitted to the nursing home she was diagnosed as being in the advanced stages and the doctors all said she wouldn't live longer than 3 years.  Now it has been 3 1/2 years.  I am worried about what this is doing to my dad.  He does have hospice out twice a week, and a wonderful nurse that comes out 5 days a week for 4 hours a day.  Any input or advice sure would help.