Looking for some advice on how to approach Aunt that I gave POA to because of long distance living situation.

The POA ENDS with death. She has ZERO control. As your father had the wherewithall to decide on whom to give POA, and made out papers for this, I am certain he must ALSO have made out a will designating who gets the remainder of his estate. He will have appointed an EXECUTOR of his estate. It is time to ask Aunt where Dad's will is (she will know this as his former POA). SHE may be the executor. She may NOT be the executor.
Now if the unusual and odd circumstance is extant that there IS no will, then the nearest next of kin who was in contact with Dad may be appointed as administrator of the estate (Executor). It is basically who applies in court to serve, and the court agreeing they are a good executor. The Aunt may already applied to be administrator of the estate. IF there is no will then the estate will be deivided among Dad's children according to the laws of HIS state, and irregardless of how he felt about the children. If however there is a will, that will will already state which siblings get what.
The house contents, dad's personal items any autos are already a part of that estate. The administrator gathers all parts of the estate together and then distributes the percentages as the state dictates in absence of a will.
Best of luck, and sorry for your loss.
Just as an aside, you did not give POA to the aunt. Your Father did. Only a person can give POA to another person to act for him or her, not that person's children. If YOU are estranged from this aunt to the extent you are unable to ask her where the will is and who is the executor then you can consider a lawyer letter from you in which YOUR lawyer asks the aunt for information of location of Dad's will, who is executor, and has process of distribution of any remaining estate been started.

If your father was in a care facility for several years, there is a good chance that all of his resources were used paying for that care, unless her was generationally wealthy or started out with more than a million dollars in his retirement accounts.

Assisted Living, Memory Care and skilled nursing facilities are very costly in the North East. 10 years ago, my mother's INDEPENDENT Living facility cost 5k per month. NH was 11k per month. That was in 2013 prices.

I’m not sure what if anything has already been discussed or transpired between you and your aunt since your dads passing on this subject but if it hasn’t already gone past this point you could approach in a very non threatening way by asking if there is anything you need to be doing, you and Dad discussed his will but you aren’t sure wether he made you the executor or not and you don’t want to hold things up by not doing what you need to. Also if you are going to need to make another trip east to take care of legal things you need to in person you want to plan that…. Something to that effect anyway. This way she is on notice that you know there is a will and probably something about it since your father had discussed it with you as well as knowing that her POA doesn’t automatically put her in charge of the will and estate without being challenging about it or anything. Fact is they are valid details and questions having nothing to do with her function or job as his POA and local caregiver. It’s not like you removed yourself and weren’t involved with your dad or your aunt, keep it about you and your responsibilities/place not your siblings for now with her.

Take the paperwork she has offered you, and go through it to see if the will is there. A will isn’t bulky, and may well be put with other papers that your father wanted to keep. Wills are usually private documents, and don’t have to be filed anywhere prior to death – check your state laws. There should be pension papers, perhaps a birth certificate, certificates for any assets, banking papers etc. If your aunt is executor of the will (which is quite possible), she is not required to provide these papers. However she should be willing to establish that she is actually the executor, which will normally mean providing a copy of the will.

If you can find nothing like that, you will have to bring it up with your aunt. Ask her to go through all the paperwork with you, and ask her if she has found his will. If you know what the old will said, write it down now. If you know that a firm of lawyers helped draw it up, contact them – wills are often left in solicitors’ strong boxes (it usually means they get to do the legal probate work).

If there are no ‘official’ papers at all, it is possible that your aunt thinks that she is still in charge because of her POA, without realising that it stops on your father’s death. Explain to her, and get her to check with legal advice if she doesn’t take it in. However it’s also possible that she is hiding the will and other papers, or has destroyed the will if she did not like what it said. If you get that feeling, you will probably need to get legal advice and a ‘frightener’ lawyers letter. It would be a great pity if the relationship ended like this, but it is always possible. Looking at the worst case, it is also possible that aunt has taken assets for herself. Unfortunately if she has destroyed the papers, you may find that there is little that you can do. However many legal matters end up being settled, which is where your notes about what you can remember about the splits come in.

I haven’t yet stated the obvious point about money. If your father’s estate contains very few assets, legal costs aren’t justified, though ‘shame’ can be important as leverage. Good luck!

I believe If there was a Will it would have to be probated and Notice published in local organ newspaper and heirs and creditors notified - that is open records.

If your father passed recently and there was no will, his estate has to go through probate, so this takes time. Even if he did leave a will, some of his estate may still need to go through probate. If you don't know who the executor is, I don't know if you can find out. If you are left anything, the executor will contact you to disperse what is leftover of his assets and property. I'm sorry for your loss.

Once he dies, no POA is in effect. Just the will is. Who is the executor of the will?