When it's her frustrations about her own abilities to cope are in Question? Mum is 75. Fiercely independent. She treats me and my sister Like dirt in public. My brother moved to QLD 9 yrs ago to get away from her. She was bleeding him dry financially living the high life she thought she deserved because she is better than others didn't you know! Well she's not. She gets no financial help from any of us now. So she winges and b^tches about that. She is close to her 2 sisters but has been pushing her friends away due to her condescending attitudes and behaviours. It is so aweful to watch.. You can't have any fun with her anymore.She bleeds you dry emotionally.
Yes I am protecting myself.
You found a way to deal with her demands for money: you don't give her any.
It seems to me that you need to continue in this manner. She is your mother, and you many not want to abandon her completely, but consider establishing strong boundaries. She abuses you in public? Why are you still doing things with her in public? She isn't any fun? Why are you spending more than minimum time with her?
You didn't fill in your profile and I don't know what kinds of impairments your mother has. That might make a difference in my answer. But based on what you state here, I say protect yourself.