According to the 1900 census, Della had 7 children and 5 were still alive. Mary and Cora may be the same person.
The 5 children at home in 1880 were Estelle, Mary, Lottie, Belle and Thomas.
Her name is listed in 1860 as Delia, in 1870 as Delta G., in 1880 and 1910 as Della and in 1900 as Geraldine. I've gone with Della Geraldine because she had a grand-daughter named Dellamere.