There are WTBTS articles that would help her understand it's not demons from a WT perspective.
Here is an excerp from an AWAKE Sept 22 1998. The whole Awake featured the disease. It may have some scriptural guidance that you persoanlly disagree with but you can censor it for your mother.
What Caregivers Can Do
“I HAVE always been amazed at how different [people] are in their ability to cope,” says Margaret, a medical professional from Australia who has dealt with Alzheimer’s patients and their carers for many years. “Some families are able to manage with the most incredible demands placed on them,” she continues, “while others are rendered almost incapable of dealing with the situation as soon as the person exhibits the slightest change in their personality.”—Quoted in the book When I Grow Too Old to Dream.
What is it that makes the difference? One factor can be the quality of the relationship that existed before the onset of the disease. Families with a close, loving relationship may find it easier to cope. And when a person with Alzheimer’s disease (AD) is well cared for, the disease may be easier to manage.
In spite of declining intellectual abilities, sufferers usually respond to love and tenderness right up to the final stages of the disease. “Words,” points out the advice sheet Communication, produced by the Alzheimer’s Disease Society of London, “are not the only means of communicating.” Nonverbal communication essential to caregivers includes a warm, friendly facial expression and a mild tone of voice. Also important is eye contact as well as clear, steady speech and frequent use of the patient’s name.
“Not only is maintaining communication with your loved one possible,” says Kathy, mentioned in the preceding article, “but it is also important. Warm and affectionate physical contact, a mild tone of voice and, actually, your physical presence all provide security and reassurance for your loved one.” The Alzheimer’s Disease Society of London sums up by saying: “Affection can help you to keep close, particularly when conversation becomes more difficult. Holding the person’s hand, sitting with an arm round them, talking in a soothing voice or giving them a hug are all ways of showing that you still care.”
Where a warm relationship exists, caregiver and patient can often have a good laugh together even when mistakes are made. For example, one husband recalls how his mentally confused wife made the bed but mistakenly put the blanket between the sheets. They discovered the mistake when they went to bed that night. “Oh dear!” she said, “I’ve been silly.” And they both had a good laugh.
Keep Life Simple
AD sufferers function best in familiar surroundings. They also need a regular daily routine. To this end, a large calendar with daily appointments clearly marked on it is very helpful. “Moving someone from their usual environment,” explains Dr. Gerry Bennett, “can have dreadful consequences. Sameness and continuity are very important for the confused person.”
As the disease develops, AD sufferers find it more difficult to respond to instructions. Directions have to be given in a simple, clear way. For example, telling a patient to get dressed may be too complex. The items of clothing may have to be put out in order and the patient helped one step at a time with each item of clothing.
If you want the whole magazine, I can email to you. Unless of course you have acess to the CD ROM, or go on jw.org and search the online library. Everything will be ok. You clearly love them very much and want to help.
What a good child you have become to them
Take care love Kate xx