You didn't show the state of birth for those on the 1880 census so I took a quick look and everyone in the household is listed as black. It's a good idea to include that in queries as it really helps to narrow down the search.
1870 census Marion Co, TX:
Duncan, Lucinda, 35, b AL " Minerva, 18, b AL " Henry, 12, b TX " Washington, 9, b TX " Gabral, 1, b TX " Sarah, 1, b TX
Compare names and dates and this matches, BUT, you notice Cynthia/Lucinda has children after the 1870 census, so there may be a problem finding the father of her children.