What can a power of attorney for my mother legally do? She is selling all of my mothers personal possesions including her house.

The Attorney in fact only has the power and authority specifically granted to them in the POA document. They do not have any implied powers or authority. In addition, since they are acting in a fiduciary capacity, they are specifically prohibited from engaging in any self-dealing. Many POA documents do however, grant the Attorney in Fact broad and wide ranging powers to deal with most if not all aspects of the prinicple's affairs, accordingly to determine if the Attorney in Fact is acting properly you must obtain a copy of the POA document. Just because the Attorney in Fact is selling assets does not neccesarily mean she is doing anything wrong, if she is using the proceeds for your mother's benefit, and the Document gives her the power to sell the assets she is doing nothing wrong