Solomon Drain and Mary Ann Holland were married in Greene Co. TN 16 Jun 1840. After Mary Ann died in 1888, Solomon remarried. He states the date of his second marriage as 5 May 1889 but doesn't mention the name of his second wife. I have not searched marriage records to find out who she was.
On the 1860 census - I see too that there is a Margaret ____ living with them. You're right, the last name is hard to read. Looks like maybe Runnels? or Russell? I don't know for certain, but I suspect she is Solomon's mother. She would have a different last name than him if she had remarried after Solomon's father left. (Solomon stated in that deposition that he knew nothing about his father except that he left his mother when Solomon was an infant).