I was designated by my parents as their DPOA and healthcare surrogate. If I sign for Mom to go to a facility, is he allowed to remove her?

Would mother be going willingly? Has she been found to be incompetent by a court? Whether Dad has the authority to remove her or not, if she agrees with him and wants to go I'm afraid it would take more than a POA to stop her (if she is competent in the legal sense.)

I think it might be good to talk to an Elder Law attorney about how to handle this. I'd start by called the Area Agency on Aging and asking if there is any low-cost legal consultation for people in your situation.

I hope you can get her placed, and that Dad might change his mind about joining her! Keep in touch and let us know.

I don’t think he can if he’s not of “sound mind”, since you hold the POA and HC surrogate papers. You would have to make very sure to let the facility know that Dad has dementia and might try to sign Mom out, and make sure they call you. You may be surprised that Dad might change his mind and decide to go too once it’s decided that Mom is going and he will be left more or less alone.