My mom sleeps all the time. What does this mean?

Dad probably sleeps 18-20 hours a day. He goes to be by 7 pm. Wakes at 5:30 am, has a coffee, then a nap, then breakfast. If he is going to do anything, he has to accomplish it between 10 am and noon. After lunch he dozes on and off until dinner.

He watches the morning news and the early evening news.

A couple times a month he meets friends for lunch. He enjoys these outings and gets himself there and back, but is wiped out for a few days after.

The doctor tried Vitamin B12 shots for my mom, we also used the sublingual tablets when it became difficult to get out.

My DW is doing the same thing. Even her walking is slower. Eating less. Watching less TV. I am actually expecting the worst. I just don't know how long this will be.
I almost feel like she is giving up. I can still get her to take her meds most of the time.
I know that I am wearing down since I can only sleep a few hours at a time. We have both lost weight.
I am just trying to keep her comfortable, fed and, clean.
I think her red blood cell count is down and she really needs meds to counter this but it is nearly impossible to get. Our visiting nurse, our Primary has tried to get it and I have visited pharmacies nearby to get this stuff. It was recommended that I double her intake of iron but so far it isn't helping any.
This may not be much if any help but I wish you the best and encourage you to have her checked by a Dr.

I see that your mother is 98. She is very, very old and I imagine that pretty much everything in her life is difficult and uncomfortable, she may have reached that point where just the simple tasks associated with daily life are exhausting.