Medical vs Moral issues

My Mom turned 80 today.
She is ‘existing’ in a home for elderly patients.
Her quality of life sucks.
She is getting good care at the facility. As far we know, anyway. It is scary to have her there under someone else’s care. You read horror stories of elder abuse and we on the ‘outside’ know nothing is happening until it’s is too late. I have not seen any signs, but what do I look for?
Her current living situation is not due to a ‘lack of caring’ on the part of any of her family members either, she has done this to herself.
She survived lung cancer and a brain tumor. We have stood beside her through all of this, as in all things. She survived this horrible indignity only to become so depressed that she does not want to live any longer. She refuses to eat, she refuses to accept phone calls from those of us who live far away. She refuses to talk to those of us who visit her daily. Every once in awhile she will say something that indicates she is living in the past. Most often she knows where she is. Sometimes she says hurtful things directed at one of us. This is very uncharacteristic of her and we try not to take it personally.
This situation is extremely difficult for us to understand. She has always been an independent woman, strong willed and very loving. She has shut down from all outside contact.
Doctors cannot tell us definitively why this has happened, they can only guess. She is comfortable where she is, or so she says. She is financially comfortable so she can pay her own way.
I look at her and want so much to have her back. I also want her to not feel any more pain.
Does she have the right to decide that she no longer wants to live in this world? I believe she does have that right. Do we have the right to grant her that wish? It is repugnant to think that one of us should make the final decision to carry out her wish.
I have known her my entire life and I know she does not make irrational decisions. She thinks things through and although she cannot always block out emotions she tries do what is best overall. She has always put her children first and I know right now she thinks she is a burden to us and therefore she does not want to continue life in this condition. Knowing her like I do is why I can say that I am convinced that dying is want she wants to do.
Do we have the right to allow her to die? Doctors, of course, take a pledge to do whatever they can to save lives but when does the patients rights override that pledge?
This is a thorny legal issue. It is a thorny moral issue. I have always been at odds over legal versus moral law.
My issue at this point has to do with a conflict of interest. Knowing she does not have a good quality life and is only waiting, indeed wishing, to die versus the medical establishment profiting on having her live.
We want to bring her home. She refuses to leave. Do we force her? I cannot entertain the idea of ‘kidnapping’ my mother and forcing her to live where she does not want to. She is a prisoner in her own body, I do not want to make her my prisoner. Has she worked her entire life collecting benefits towards supporting herself in her retirement years only to have all of it go to the medical establishment? This scenario is just plain wrong. It is wrong that they are benefiting from her condition and we all hopelessly stand on the sidelines and can do nothing.
There is no easy answer to this, the greatest, and most painful moral dilemma this family has ever had to face. Of course we try to keep her as comfortable as possible. This usually means drugs. This means giving up independence. She has now become dependent on a pill to keep her numb. The medical establishment charges exorbitant rates for everything they control and administer. How long is this going to continue? For my mother, no one knows. For the medical establishment, forever.
There is only unsolvable issues while the medical establishment continues to profit.