Unfortunately, a Power of Attorney is no longer valid if the Principal dies. The purpose of your POA was to allow you to act on your Mother’s behalf during her lifetime. At her death, the POA automatically terminates. Now you must qualify as her Executor (if she has a Will) or Administrator (if she does not) to deal with her assets.
Learn more about Power of Attorney by following this link to our other articles about POAs, or speak with your lawyer for consultation on your specific situation.