Wordorigins.org

Homecoming is a peculiarly American phenomenon. It is a reference to alumni returning to their school for a visit, associated festivities and a big football game.

The term dates to at least 1913, when it is used in a 16 November article in the Chicago Daily Tribune:

Illinois, fired to superhuman endeavor by the presence of a big crowd of homecoming alumni, not only fought the confident Purdue team to a scoreless tie but also threatened many times to claim victory.

Some claim that a homecoming is a game played on one’s home field after a series of games on the road. This is a minority usage and not the original sense.

(Source: Proquest Historical Newspapers)