Get your mother out of there and some help if you can

A lot of people don't really understand what these relationships are like, and they are quite common. A spouse with narcissistic tendencies and a powerful, overwhelming personality controls the family unit, and the other spouse is a timid, meek or submissive weakling who has no self-esteem and locks in with their abusive partner like two broken magnets sticking to each other. The narcissist feeds on the scapegoat partner who gets to feel like a victim and thus never has to change his or her life situation. Every conversation will be the same "I couldn't leave, I'm too scared what they would do." Then you offer help, plans, options and they keep finding more and more excuses to not leave, to not change.

The sad truth is they want to be there. Not because it makes them happy, but because they have become addicted to the dependency and victimhood, it absolves them of responsibility for themselves or anything and they never, ever leave.

I went through all this with my own mother and my narcissistic monster of a father, I tried to get her out many times, brought her to my house, she had a meltdown, then went back to him. Over and over.

Eventually she did get out. Unfortunately it meant me signing for her life-support to be turned off. At least she's free.