I guess '900' is the old traditional song. The popular 60s folkie version deals (mostly) with '500'. It was first done by The Journeymen (including young Scott McKenzie) in 1961. Followed Peter Paul & Mary in 62 to make it a hit. The New Christy Minstrels did in 1962 a 900 miles-version. Probably same tune, but not really sure. Hedy West and Bobby Bare, who are named as co-writing the 500-miles version of the song, according to the the BMI-archives, recorded it in 1963. BMI registers '500 Miles', aka '500 Miles From Home'.

BMI registers 5 times a song '900 Miles' or '900 Miles from Home', but the composers mentioned are unknown names to me.