In the 1870 Federal Census, Mary is age 41 and living with her second husband, Sylvester Wilder, age 60, in Randolph, Crawford Co., PA. Her son Frank, age 12, is with them. Frank's surname is included in the list as Wilder.
In 1880 Sylvester & Mary S. Wilder are ages 70 & 50, and are still at Randolph, PA.
In the 1900 Federal Census, Mrs. Mary Wilder is a widow age 70. The census data says she was born in PA, but her parents were born in NY. All the other censuses have NY as her birthplace. Living with Mary is her granddaughter "Margret G. Lipet" age 6, PA (born Feb 1894). They are at Randolph, Crawford Co., PA.
Whose daughter is Margaret? She is probably the daughter of Frank F. Lippitt by his first wife, Addie Guy.