It is extremely difficult to help someone who does not want to cooperate. You see their needs, but they refuse to let you help them.
From what I recall from our previous conversation, we suspected that your mother might have a personality disorder. If she does, then her insight into her own problems and how she treats others is going to be minimal, if it exists at all. Add to that her age, which contributes to her being set in her ways, and you have a very tough situation.
If she is willing to see her regular doctor, you may be able to have him/her talk to your mother about seeing a therapist or psychiatrist for an evaluation. The doctor can "prescribe" the visit, which is not really a prescription, but if your mother feels the doctor wants her to have this done, she may be more willing.
Also, learning what you can about personality disorders will help you figure out what might be going on with your mother and how to react to it. It is very frustrating to want to help and the person resists. But that is the nature of someone with your mother's issues. The best you can do is be there for her and do the things she allows you to do. Unfortunately, she will eventually need full time care and won't have a choice. That is when you and your family can step in and do what you feel needs done.
Consider talking with your local Area Agency on Aging for more input and support. They work with people like your mother every day and know what resources you can use in your area to help you and her.