Is there anything we can do?

Is there a will? If so, that ought to determine who the house and its contents belongs to. If there is no will - probate must be filed with a judge appointing an executor.

Two things to keep in mind - POA ends with death. So once your FIL passsed, she no longer has the authority to act on his behalf. Although, it's very likely the joint checking will divert to her solely - and any other account she may be on. Just hope she is not named as executor of the will. You will likely need to get an attorney and/or your local sherif involved to get the house keys.
The second thing is that POA is not allowed - in any state - to make changes to a will. So unless she took your FIL to an attorney for a new will or changes to an existing one - if there is one - the will, will stand as originally written in a court of law.

Good luck - I think your gonna need it as this sounds like you're going to have an uphill battle on your hands.

P.s.  I'm curious- if she wasn't living in the house and had a husband at home I'm assuming she spent time with - who looked after your FIL when she was at home with her hubby?

...AND - it's my understanding that a POA can only change a beneficiary to a life insurance policy IF that power is specifically spelled out in the POA document. Unfortunately, it's unlikely this woman is going to share the document with you willingly so you might not know what powers were and weren't allowed without a court order.

Additionally- if the POA document does grant the power to change insurance beneficiaries and she changed it to herself - she could be placed under an investigation by the insurance company. Doing that - changing beneficiary to herself is generally considered unethical - an abuse of power and if challenged could negate the change.

That woman sound suspicious. Run and get an elder attorney because it sounds like a case of elder abuse. I don't know of too many people who would "befriend" an elderly person unless there would be something to gain. I don't know how substantial your father's assets were but they must have been substantial enough.

Do you believe she coerced him into these things? Did FIL have dementia?

What is your evidence that FIL did not do these things of his own free will?

What was the nature of your relationship with FIL while he lived in that house and had that woman as a nurse?

There are so many questions here. Were the bank account and insurance beneficiary changed in the two weeks the CG was his POA? Or long before?

You don't mention anything about FIL being mentally compromised. So I assume that he made the changes and that you are thinking it might have been under duress -- that CG Nurse put pressure on him or exercised undue influence. I think you will need evidence that this happened. What can you point to suggest unethical behavior?

You can't just waltz into a bank and say "Please add me to Joe Doak's checking and savings accounts." Your FIL would have had to be there in person, which is perfectly possible in a wheel chair. So, assuming he was there and changed it, what did she have over him to coerce that?

It is similar with beneficiaries of an insurance policy. It may not require personal appearance but you can't just dash off an email and say "change the beneficiary to me, please." You father would have had to authorize that.

On what basis does she claim that the house and contents are all hers? Is that in a will? Or does she claim an oral agreement? Was her name put on the deed? When?

Please understand, I am not trying to argue that the Nurse was an upright citizen, devoted to caring for one at-home client and FIL thought she should be rewarded for her devotion. (That is possible, of course.) But I think to change anything you will have to prove malfeasance on her part. That will take evidence. I do understand why you are outraged, but that is not enough to change the beneficiary or account ownership.

You (or your spouse) will need a lawyer to guide you on this.

The house was a rental, we just want in to get his stuff and paper work, but it has been a week and I am sure she has cleared anything we will need. He was at an OK state of mind. He was an alcholic, we tried and tried to get him treatment, but she kept him happy with his drinks. I am sure knowing him, she flirted alot and kept him drunk, not that she forced him to drink. She knew that family relations were not great because of the drinking. and used that to her benifit. My husband had seen him 3 days before he died and did not mention that he changed the POA. I like the idea of finding the attorney who helped change it. We wonder how many life insurance policies she has on him. We will probrably never know. No 401K or retirement. Thanks for the advice.

Also you could tell her you are going to file a complaint to the State Board of Nursing if she doesn't cooperate.

If she works for an agency chance are there are all kinds of rules regarding accepting gifts, handling money etc. while this might be enough for her to loose her job, there is a chance she might have signed some sort of contract or agreement in order to work there - which may be to your benefit if you challenge her claim to bank accounts, insurance money, etc.

I would investigate to see if she has taken advantage of other elders in her care. Google her name and also look for complaints registered at the State Board Of Nursing. You need to file a complaint with them, the VA, police and Elder Services.

I imagine it's a matter of proof - why they don't arrest her. She's probably telling the police your FIL gave her the items she did return and claiming she never saw any rings, gold etc.

Which brings me back to a question I asked earlier- if she has a home with a husband in it and she lived there at least some of the time - who looked after your FIL when she wasn't there? If there was additional help they might be able to provide you with some concret information regarding your FILs personal belongings.