Do elderly people stare up at nothing at the end of life?

I care for my 92 year old grandpa, and he had 2 strokes in his cerebellum last month. He has been coherent and fine until about a week ago. His speech is slurred and you can barely understand him, and I've noticed that he stares up at the ceiling and talks (or mumbles). I can't understand him but his eyes are usually closed as he drifts on and off to sleep. He talks to children and thinks he sees and talks to other people who aren't there in the room. He hasn't spoken to anyone in the family that is deceased, but he did call my sister his sister in laws name who passed. I just don't know what to expect and he's going downhill so fast. I was just wondering if anyone else has had similar situations where the person was always looking at the ceiling like something or someone was there and maybe what it meant. Thanks