How can my mother go about getting a notary to sign statement for child if my mother cannot get out of bed or leave the home?

My mother has full custody of my niece who is age 15. My mother just had reconstructive hip surgery and is unable to get around and take care of herself, let alone the granddaughter. The granddaughter wanted to live with her biological mother who resides in Pennsylvania, so my mother let the child go; however, the biological mom cannot get girl in school due to needing a noterized statement. The kid has missed 5 days of school. My mother cannot get out of bed or house to go to notary to get statement for biological mom to enroll kid in school. What can be done to alleviate this problem? Grandmother resides in New York.