Can a durable power of attorney remove two beneficiaries from the principal's annuity and claim it was his decision, despite him being non-communicati

The POA claims that the principal wanted these two beneficiaries removed from his annuity and that he told the POA of his wishes for the 5 months that he was hospitalized and comatose from a brain aneurism. the POA claims that he wrote his wishes on a note. In other communication, the POA explained that he was non-communicative and couldn't write and could only mumble. the POA spent hours and days with the principal while he was comatose and could have very possibly been persuading him to alter his annuity without him being in the right headspace to make these important decisions. The principal died yesterday and the POA claims to have removed the two beneficiaries and transferred their inheritance to herself, claiming that it is what the principal wanted. Is this true? How can we know what he wanted? the POA also claims she communicated with him more thoroughly than the doctors did.