I don't think this is the Margaret McClelland you are looking for:
1900 Philadelphia Pennsylvania - Maternity Hospital
Margaret Mcclellan age 30, born Jan 1870 Ireland, married 1889, immigration looks like 1886, 5 children 3 living, occupation housekeeper
1910 Philadelphia Pennsylvania
Margaret Mcclelland age 40, born Ireland, widow with 3 living children, servant for private family