POA revoked. New POA and live in caregiver. Advice?

What is he doing to intimidate her? Can she call 911 to report feeling threatened? Tell her to do this. Otherwise she will need to go through the eviction process (and it differs from state to state): fill out eviction form, submit at the courthouse and pay the fee, post the eviction notice where the form says to, after the allotted time (usually 30 days but check the protocol for your state) then the residents MUST get out. The police don't like to come to these situations since this is considered a civil and not criminal issue. But after the allotted days you can threaten to have them escorted off the property. Then your mom might want to consider a restraining order if he turns into a bigger jerk. Just wondering what possessed her to make him her PoA to begin with? If she is not diagnosed as incompetent then he has no power over her no matter what. Does she know this?

He is considered a resident and as such will need to be evicted. Even though he paid no rent. I would do this as legal as possible. If he is told he needs to be out by a certain time, you can have the police there to help him be escorted out. Make sure he takes everything. Tell police there is no coming back.

I am afraid in trying to make this short and sweet for us it ends being not understandable, to me at least.
Let's start with the basics.
Who is she and who are you in relationship to her. For instance, Mother and child, or ______________ and _____________.
What relationship was the previous POA and caretaker?
How was it proven the previous POA was committing fraud and was this in court?
Has an APS or Court case been opened.
I am assuming "she" is competent, as this would be required to rescind and make another POA. If so, she should likely see an attorney to begin proceedings against the person who committed the fraud. Then should go to the police and say she is being threatened and intimidated in her own home by someone who has controlled her and her finances and has committed fraud.
There should then be legal action to evict the person from the home.
I am trying to go on the little I have to work with. There need not be a rental contract or payment for a caregiver to be considered a tenant, and Missouri law best explained by a Missouri Lawyer. I assume that when the first POA was rescinded/ new one appointed that there was a lawyer present (or certainly HOPE so). That lawyer should be able to answer your questions for your State's laws. Wishing you good luck. More information may allow us to answer better/or more fully.

Oh, his mother can stay until her family finds suitable living arrangements, she's elder.. Im not a monster lol.

How did you get the cared-for person to revoke the original POA if she is intimidated and wholly dependent on him as her live-in caregiver?

No contract, rent, no pay - is this a close family member, her son perhaps? If that is the case, as I think you have already guessed, there's nothing simple about the removal or anything else in this can of worms. If not - who on earth is he and where did he come from?