Power of Attorney?

Hello, my Great Aunt is currently in a nursing home. She is 88 and has dementia and really has no clue who anyone is anymore. The social worker would like us to complete a financial and medical power of attorney for her. I know this should be done since there is no one to handle her affairs. She really doesn't have much of anything but I am sure this is still good to have. We do not have the money to involve a lawyer and the nursing home said you can print the power of attorney off line and they have a notary available there. We did this and took them into her.. she is no longer able to write so she signed with an X and the notary in the room noterized this.. is this now legal???