1850 census of Floyd Co., Virginia, western district 15, enumerated 29 Aug, lists on p. 873 as family #831:
Rebecca Sutfin, 33, b. Carrol; Bethana, 13, b. Floyd; Asa, 4, b. Floyd. (Carroll Co. was not formed until 1842, so that probably means the part of Grayson Co. that became Carroll.)

1860 census of Floyd Co., Virginia, Greasy Creek precinct, enumerated 17 Aug, lists on p. 166 as family #1192/1113:
Rachiel Sutphin, 27, housekeeper; Catharine, 8; Lyrand, 1; Rebeca, 43; Bethany, 22; Asa, 14; Elizabeth, 9; Harmit, 6; Ellen, 5/12.

Rachel is probably Rebecca’s sister, not her daughter, since they were not living together in 1850.

I have not found Rebecca in the 1870 census. Rachel is in a household with Bethany and her children:

1870 census of Carroll Co., Virginia, Pine Creek district, lists on p. 115 as family #134/138:
Sutphin, B., 33; Clery L., 1 (f); Stone W., 8; Rachel, 39. All born in Virginia.

1880 census of Carroll Co., Virginia, Laurel Fork district, lists on p. 9 as family :
Sutphin, Bethana, 43, keeping house; Stonewall J., 18, son; Clara E., 11, dau; Barbary E., 9, dau; Mary M., 6, dau; Wiley Lee, 3, son; Rebecca, 63, mother.

The preceding household is headed by Rachel Sutphin, 48, and the next household is headed by Eliza Sutphin, 47.