Adult protective service harassment. How can we get this to stop?

First I have to ask...why are your husbands siblings involved with YOUR parent. (to coin an old phrase..they have no horse in the race)
What I would do...
Consult with your Elder Care Attorney about the complaints.
I would say do not answer any questions I would refer them to the Attorney
(By the way all calls to the attorney and any expenses are paid out of your mothers funds not yours.)
They do have a right to make sure that your mother is cared for, in good health so you do have to allow inspection for that. But I would have a witness and if possible video the inspection and record any conversation. (If you have security cameras that record this would be a great use for them) Make sure that there is a notice on the door that security system is in place. Audio recording has to be agreed on by both parties but video is legal with out audio.

Skipperdude, I would consult an attorney. ASAP.

"Myself and my spouse are taking care of "my Mom" this is very misleading. I did look at you profile and saw its ur MIL.

I agree. APS does not keep coming back. Maybe they reported back to the sibling and he wasn't satisfied with their findings. Maybe they froze the acct to keep the sibling happy? If Moms account shows deposits and withdrawls and you can back up the withdrawls, I don't see why they keep coming back.

This may go down like a lead balloon, but it is obvious from many comments on this site that other people really do think that the carers are doing very well financially out of caring. Perhaps another approach would be to invite in your wife’s brother, and give the information about costs to him direct. Not Alva’s full list of bank account numbers etc, but just an overall picture of finances, tasks and times. If he genuinely thinks that something is wrong, (and even if his motivation is jealousy or to keep a bigger inheritance for himself), this could repeat over a long period of time.

Hhonestly? They've been to your house more than once and they're freezing bank accounts, which means they have reason to believe there is some truth to the accusations...even if there is none. Were I you, I'd hire an attorney and let him/her do my talking for me.

Your best move now is to be COMPLETELY willing, open and forthcoming. When you are POA and you manage the care and finances of an elder you must keep meticulous records of everything, every account, every transaction. When I managed my bro's trust and was his POA I kept month accountings of every penny in and every penny out, and I mailed a monthly accounting to him, as well as keeping in a folder in my "wine box" files. I had a seperate manila file folder for every expenditure from insurance, to phone payments, to everything. Even his charge card I kept meticulous records as to what each charge was for. Had APS come in I would have made them a pot of coffee and croissants and sat them down with everything, as well as the name of the bankers at each bank that helped me. At this point it doesn't matter who reported you. But it is of interest that they are returning. What is their explanation for that. Don't make them dig. Make your life an open book. This will be your best way to get the wolves away from the door. If you have done nothing wrong then there is nothing for them to find. As you can well understand if you read the forum there are many people who DO do it wrong, and who embezzle from parents and spend on themselves. This is the reason APS exists. Welcome them. Do be aware that the best thing siblings can do is to get along so that parents are not torn into two pieces over their squabbles. And know that if anything enters into court the guardianship will likely go to NEITHER sibling, but to the state. This will mean that no one has any say in the elder, not regarding even placement nearby where you can visit. It is something you definitely do not want.