Not sure if this is the right Anna, but the following census record appears in West Hempfield Twp in the 1880 census, page 37B. An Anna Mumma, age 76, widow also appears on this page. Age is correct.
Father:Abraham MUMMA (b. 17 JUN 1836, PA - d. 7 JUN 1924, Lancaster Co., PA) Mother:Elizabeth "Lizzie" THATCHER (b. 4 FEB 1845, PA - d. 25 OCT 1936, Salunga, Lancaster Co., PA)