I know Milas A. Gheen and his wife Rachel McCrary had a daughter named Margaret H. Gheen who married Daniel Edward Helfer (Helser?) and they appear on the 1900 Cocke Co., TN census.I haven't been able to find them in 1870 or 1880.Estate records of Milas (in Rowan Co., NC) show that Margaret and her husband lived in TN at least by Dec 1869.
Margaret may have been the daughter of Polly Brown? and not Rachel?According to the 1900 census she was born Aug 1848 - and Rachel and Milas married Aug of 1848.So, I am not sure if she was pregnant when they married or if her mother was Milas' first wife and he married within the month of her death - or of course the census could be off.
Margaret had brothers William Thomas Gheen, Joseph B. Gheen, and John H. Gheen.
Milas' widow Rachel married Thomas Sloan in the spring of 1867, but the 1880 census of Rowan Co., NC shows her status as married, but there is no one else in the household but Sarah Eliza Gheen (Milas & Rachel's youngest daughter).
I am just really starting on the Gheen family, but maybe your Ruth was a grandchild of Milas & Rachel, and the daughter of one of Margaret's brothers.