Legal Question in Wills and Trusts in California

Definitely not. POA is intended so that when the person can not be available another person can carry out their wishes. It does not grant greater authority to the holder than the person making it has. Since your mother no longer has the mental ability to make decisions, the holder of the POA also has no ability to make those decisions. The POA is effectively revoked. You need to apply for a conservator or her assets or a guardian for her.

Mr. Sher's is correct only if the POA is not a durable POA. A durable POA survives the mental or physical incapacity of the grantor of the power. However, to my knowledge a POA never carries the authority to make or change a will. I'm pretty sure that cannot be delegated by a POA. Once a person has lost the mental capacity to act, their will is stuck the way it is.