He continues to work and my mom goes to a senior center. When he is home he is miserable and nasty to her. I have offered my help and support (I work in a nursing home I have a lot of education about the deuterating effects of this terrible disease). His Daughters live in Buffalo, NY. My only sibling lives 200 miles away and is not as close to my mom as I am. My real Dad sexually, mentality, verbally and physically abused us. We finally went into hiding. Then at 13, Dennis (the stepdad) came into picture leaving his 5 children and wife for my mom. He told me not to expect him to talk to me. So, here we are now 35 years later. Mom has dementia and will not allow my help or caregivers. He is so stubborn. WELL SHE FELL TAKING THE DOG OUT, BROKE HER ARM AND SHOLDER. HE STILL WONT GET HELP! Because of my childhood, both my mom and I are nervous all the time and suffer from EXTREME Anxiety and PTSD. I need help. I don't know what to do anymore. People say just back off him. She told me the other day it's like living with my dad again. I almost died. He may not beat her, but he treats her like she's stupid all the time.
Hopefully your mom won't do what my MIL did with her loser husband: get her kids to move her completely out and then 3 weeks later he told her he was "suicidal" (no, just a good narcisistic manipulator) so she moved back in with him. We told her to NEVER complain to us again or call us to help her with that situation, and we meant it. As they both aged poorly we got her out of their home and allowed the county to become his guardian when he thought we'd take care of him with his Parkinsons and poverty. Nope, he died all alone in a crappy Medicaid facility. My MIL is now in LTC in a wonderful place 3 miles from us, also on Medicaid, but well cared for.
Does stepdad own any guns? This would be important to know in advance... you can't be sure how he will react. Don't even hint to him about your mom leaving unless you want to kick the hornet's nest. Make sure your mom understands that if you help her out she stays out or you'll not help her move back. She cannot divulge where she is or who helped her.
Finally, I would contact his daughters and just let them know that you don't think their dad is doing well (PTSD, anxiety, possible dementia). They may not want or be able to do anything about it, but at least they can't say "we didn't know"...
If she wishes to come live with you are you willing for that to happen?
If she wishes to leave and get her own place, see an attorney and separate her assets (finances) from his, are you willing to help with that?
If you offer that and she refuses there is nothing you can do. Getting a guardianship would be expensive and likely a risk to your life.
I would talk to APS. Your stepfather is her next of kin.She has been living with abusers all her life.
Again, I seriously doubt, if the state cannot help, that there IS any help. Not everything in life can be fixed. You can only report her as senior at risk. You yourself are helpless to interfere. And, again, have been ALL YOUR LIFE for the choices your Mom made. Again, not everything can be fixed. This isn't your responsibility; you did not do this and it isn't your fault.
I honestly would separate my life from these people and would have done that long ago so I could get therapy and have a life worth living, thus breaking this cycle of abuse.
I suggest you read the book Never Simple, a memoir by Liz Scheier, in which she spent decades trying to help her Mother with the state of New York and with the social workers of NYC. Went nowhere and could not be done no matter what.