I don't think 90 is too old for a quilt. It will be an heirloom quilt by it's very nature that can be passed on to maybe her oldest living child and then to the next oldest and so on as the siblings pass away. That way everyone in the family should get a chance to have the quilt, theoretically. It is possible to do a two sided quilt too. You could have all of her children's names on the front and all of her grands and great-grands names on the back. You could even utilize two different album quilts, one for each side. Sounds like a fun project, how very generous of you to offer to make it for her. Best wishes with the project.