My mother described to me some recent "hallucinations" that she has been having--I'm not sure that is the correct word. They only occur at night when she is in bed. They often awaken her in the middle of the night. I'm wondering if they are dreams rather than occurring when she is awake? During the day she does not have them. A common one is that she is awakened when she hears someone knocking on her bedroom window, calling either her name or "help." Recently she has begun seeing a person in her bedroom in the dark. The other night she said a "gnome" was walking in her room and came up to the side of her bed and covered her with a blanket. She thought it was a gnome, but in the darkness, she felt the gnome's face and it had the face of her husband. So then she thought it must be her husband walking around the room on his knees and she thought this was strange. My father denies he covered her up or was walking on his knees. He reminded her that many years before she used to think there was a neighbor man standing outside the bedroom on the lawn, smoking cigarettes. My mom said she could smell the cigarettes and it would make her so mad that he was smoking on their property. In the morning she would go out to the lawn and look for cigarette butts.
My mother realizes that a gnome could not be walking around her bedroom. I think it is probably dreams. They seem real to her. She takes citalopram for mild depression/anxiety and to help her gain weight. Recently, her doctor added bupropion to that because my mother complained of feeling tired. My mother wonders if she could be having these hallucinations because of the bupropion. I know that some psych meds do cause more vivid dreaming. Could that be what is going on?
For context--my mother is 86 and has shown cognitive decline in the last couple of years. Her memory is not good anymore and she doesn't think as clearly as she used to. I guess she probably has early dementia, so I wonder if these "hallucinations" could be one more symptom of dementia? She is also under a lot of stress as she is the main caretaker of my father, 88, whose health is not great. He is on dialysis and goes back and forth on whether he should just end his life (by stopping dialysis). They both still live independently and can do their ADLs. My mother still drives. They both have had falls in the last year.
I'm not sure what I am asking.

Are these "hallucinations" a cause for concern? Just dreams? Are they a part of dementia? Could they be due to the bupropion? Due to stress? Any insights are appreciated.