In the Federal Census of 1870, Clarissa Davis is age 53, living at Plainfield, Sullivan Co., NH, keeping house with Phebe Johnson. Clarissa's daughter Martha Beers is also in the household. Apparently Clarissa & Amasa are not together, at least not as listed in the census.
In 1880 Clarissa Davis is age 63, still living at Plainfield. She is with her married daughter Martha (Beers) Jondro and family.