Nancy Jarrell Fluty-wife of Francis Fluty

Nancy Jarrell was 2nd wife of Fransis Fluty of Lawrence Co KY. On 1860 census Francis is 60 and Nancy is 18. In same household is Mary Marcum 24(house servant) Ransom Marcum 3 William Jarrell 3 Samuel Marcum 2 and Harman 1
Francislater died in 1860. In 1880 census is William H Davis 52, wife Mary 44, daughter Mary 21.Ransom Marcum 23 stepson, America 21 stepdaughter, Harry Lee 1 stepgrandson and Hiram Jarrell 20 -ward.
Can anyone give insight on why Harman/Hiram ( he was son of Francis Fluty and Nancy Jarrell Fluty) was a ward ofWilliam Davis and his wife Mary Marcum Davis in 1880. What happened to Nancy? Why was Hiram listedas Jarrell and not Fluty in 1880? And who was William Jarrell?
Thanks Marsha