When would sleepiness be something that should have a doctors attention in a 95 year old lady?

I am actually only giving moral support/encouragement to my friend who is caring for his 95 yr old mother. She is very slow moving in getting to the bathroom or anywhere else for that matter, Has neuropathy in one one foot, a a result from knee surgery many years ago, is incontinent some of the time. She seems in the last few weeks to be "very far away" and says she can feel her deceased husband in the home. Sometimes is very alert and has a quick wit and up until recently was very interested in doing the daily crossword puzzle in the newspaper. Now some days she is not so interested.and is excessively sleepy. She still wants to go out to dinner as she has been accustomed to but can't seem to get the energy to do so. My friend asked his mom if she was dying and she said yes. I'm worried about him as I'm afraid he may be headed for burn-out as he has had most of his mother"s care on his shoulders for just over a year with only two short breaks. I have gone down to Florida where they live to help about 5/6 times in this past year, and each time I see a decline. IS EXCESSIVE SLEEPINESS SOMETHING THAT IS NORMAL FOR HER AGE OR SHOULD SHE BE SEEN BY HER DOCTOR? sometimes the sleepiness can be as much 18 hours in the day. Thanks for your reply in advance. Mary