*JacknJill, your mother is being utterly unreasonable and needs to be pulled up fast. make it clear to her that any help from you is dependent on her making an effort. Refuse to push her in the wheelchair. Tell her you have injured yourself once and next time could leave you in a situation where you could not help her at all.
She is emotionally black mailing you. You have to learn to say 'no' to her. Get her fixed up with a call alarm, so that you can ignore calls if you do not want to reply to phone calls. Your mother clearly has all her wits about her, even if she has physical disabilities. She should be capable of organising her own life.
I know it would be nice to have a solution that does not require you to anger your mother. But we all know that is impossible. One at a time, itwm by item, force her to look after herself.
If she throws the personal alarm across the room and then makes sure she falls out of her chair so that she can blame you if no one finds her for several hours, you could point out that she has never not been able to phone you because she has dropped the phone. That everything was set up for her deal with the situation, but she chose to put herself at risk.
It will be hard, traumatic and deeply troubling, but there is no alternative - and you know it.
Discuss it with your family, enlist their support and gradually prise the hold your mother has over you. Your mother could live another 10 years and if she does, and you do not do something, you will die before she does.