Has a College Football game ever ended 56-2?
Exactly once. On October 25, 1975, Colgate beat Lafayette 56-2, and no College Football game before or since has ended that way. When it happened it was a scorigami, the first 56-2 in league history.
That makes 56-2 the 1819th most common final score out of 2,215 that have ever occurred in College Football. One point away, 57-2 has happened 2 times and 56-3 has happened 36 times.