My Mother is 93. My sister has power of attorney. There is money in an account in both of their names. If my Mother dies is the money now subject to inheritance laws, or can my sister continue to just access the account??
If the account is jointly between your mother and your sister, upon your mother's demise it becomes your sister's money.
There is an exception if you mother demostrates that it was solely planned to be a convenience account for her, without the intention that it was to go to your sister. Such use would include for funeral expenses. However, this is difficult to establish.
If your mom dies, the money belongs to your sister.