How do we get a nasty dementia patient out of their home and into my house for care?

I would advise against doing this. Bringing her to your own home, that is.
I would advise placement and visits. In care facility.
If you are POA this is in your power. If not, then not.
If you do EITHER/OR you can do so by EMS if you are POA. Ambulance transport; likely you will pay, but that's another thing.
Good luck.

If Mom is 90 then your in your 60s? A senior too. You do not want to bring your Mom to your home. She is 24/7 care and you will resent it. She has lost the ability to reason, empathy is gone too. They become self-centered and all about them. Your parents both need care in an Assisted living and Memory care if they can afford it. If not Mom at least in LTC with Medicaid paying for her care. Their assets get split and moms share gets spent down then Medicaid is applied for. Dad can remain in the home and have enough or all of their monthly income to live on.

Yes, may need to take advantage of a hospital stay, Rehab is better. You ask for a 24/7 eval if found she needs 24/7 care then u transition her to Longterm care or MC whatever they can afford. Do not take her home. Say its an "unsafe discharge" and at 94 Dad can't do it any longer.

Has Mom been formally diagnosed. If so, she may need meds for her paranoia so call her doctor. If not, you can't really do much without a diagnoses.

My first reaction was "your Dad needs to get a spine." My sister's in-laws were exactly like this. Dad who started out to be the healthier of the 2, wouldn't do anything other than what Mom wanted. He was loyal to the bitter end. He would carry her up and down one flight of stairs all day long. She didn't want to live on the main floor; she had to sleep on the 2nd floor. He wouldn't go grocery shopping because she didn't feel like it. He wouldn't eat a meal because she didn't feel like it. He died before her of heart disease. He just didn't take care of himself because it interfered with what she wanted out of him. He was in ICU twice before his death. Mom never let up until he was in hospice, the last time.

So what I'm trying to tell you is that your Dad and Mom's dynamic, is quite common. Given that, it does beg a different question. If your Dad wants out, can he find another place to live? Maybe an assisted living center?

I really don't think you want either of them to live with you. You will need time away from either and both. Hard of hearing is very difficult to live with. Hearing aids are not the complete answer (I know because I now wear them.) Maybe you could put him up temporarily while he waits for an AL unit at his preferred place, to open up. Because of your Mom, you might find out that Dad is high maintenance. It might take time for him to become a responsible person again.

Your Mom knows exactly how to get your Dad to do what she wants. However, unless your Dad "grows a spine", nothing will change. I'd work on getting your Dad to do what he wants to do. If he does move away from your Mom, he will need your support as he starts to learn how to live without her. Your Mom, regardless of whether you realize it it or not, is perfectly happy with the way things are right now.

Only your Dad can change the dynamics.

If you think things will get easier when she’s in your home, you’re wrong. We’re talking about your own personal hell here. Please find other arrangements for her so you won’t be coming back to vent when she’s driven you totally out of your mind. I’m sorry for your predicament, but it’s a predictable predicament and you need to get out of it before you get in.

"How?"

I'm also thinking *Why?*

Why do you want to move a "nasty dementia patient" into your home?

Maybe it’s your dad who should move to your house. I’m not sure it’s a great idea to do that since you might end up with both of them but it sounds like a really bad idea to move your mother in especially kicking and screaming and it may be that the only way to get her out of her house, evaluated for any other medical problems that might be making this worse (UTI for example) and HC, AL, NH or MC is for an emergency to land her in the hospital. Your dad around trying to take care of her is simply wearing him down and not actually helping her or anyone else. Your dad may decide they should live together in AL or that he will go back home to live alone there once she is gone but none of that can really be considered until your mom gets the help she needs by giving your dad the separation he needs rite now.

Gratefulgranny, welcome to the forum. For some of us here, the only way to have a parent leave their home was to wait for a medical emergency. 911 is called, stay at a hospital, rehab, then moved to a new place for care.

One can use a "therapeutic fib" saying the doctor wants the person to be here until they are physically ready to go home.

Now, on a side note. are you and your husband ready to have someone live in your home who will not cooperate with anyone?