Yes it is.
The house is the mother's.
It was put in the children's names for estate planning purposes and not for ownership while she is living.
To sell the house or make any decision that benefit the attorney under the POA or any and not the mother is prohibited.
That money is for the mother's care and use until she dies.
I hope that helps.
It doesn't matter how much money she has.
It's fraud to take her money because she is incompetent.
It's not legally possible.