IF--and it is a pretty big "IF"--the Barbour County, AL, Martin family is his--the family was still in Barbour County in 1930.And IF that is so, a slightly younger brother was named Daniel (1915).
A man named Daniel Martin, born 1915, died in Eufaula--Barbour County--20 SEP 2003.This COULD be Tom's brother.
You will have to get into local newspaper archives to see if there was an obituary--try the town and county library. You might consider writing to the local newspaper and seeing if they would print an article about your search.
Eufaula is south and across the river from Ft. Benning where Tom enlisted, so without pushing any of the possibilities too hard--all of the pieces of the puzzle seem to fit.That is IF the family of Daniel is the family of Tom.