According to p254-255 of The Fisher Scrap Book by William L. JONES, James DARK & Sarah W. FISHER moved to Johnson Co. IL in 1854 & moved to Hollow Rock, Carroll Co. TN abt 1869 and James died soon after. Sarah married a Mr. BUFORD. However, I was not able to find a marriage record to BUFORD or find them in 1880 census. I did find a marriage record for Sarah W. DARK to James D. DUKE for 24 Sept 1872 in Benton Co. TN. Sarah DARK & son John were living in Benton Co. in 1870. John mar. Mary E. SWIFT 22 nov 1869 in Benton Co. There were no other DARK family in Benton Co in 1870.
J.D. DUKE and wife S.W were in Dist 16, Carroll Co. TN in 1880 & S.W. was born abt 1824, which is abt when Sarah W. FISHER DARK was born. J.D DUKE was age 85 in 1880, so its possible he died and Sarah married again, but I didn't find her in 1900 (& she would have been 76). There are not very meny Carroll Co. cemeteries online & I was unable to find any DARK or DUKE or BUFORD in the ones that are.