This data may or may not be assistive. I add that I have no connection to this Keenan lineage. The information was found at Ancestry.com. Some of it was from submitted family trees which are always suspect until the information is verified and documented. Caveat emptor.
Following Frank B. Keenan listed in the 1880 Federal Census for Berlin, Jackson County, Ohio: Line 7, page 4. Father was Milton C. Keenan, born c 1843 in Ohio; mother Deborah Tuttle Johnson. Milton died abt. 1890 in Jackson County, Ohio. He had married Deborah 7 May 1863 in Jackson County, Ohio. Milton was the county treasurer according to the occupation listed in the mentioned census.
Milton's father was Beverly C. Keenan, born 10 Sept. 1810, West Virginia (it was yet Virginia at that time). Milton's mother was Martha McClure.Suggested father for Beverly C. Keenan was John Keenan and mother was Mary Williams. Good luck.