If you're going to the U19s game at 13:00 (Fohlenplatz stadium next to main MG stadium), then getting across to Rheydt before the evening game is probably a better idea than travelling back towards MG as the old town drinking area in MG is about 15 mins walk from the bus station, whereas in Rheydt it's more central. However, it might be an idea to grab a taxi (if possible) to Rheydt after the U19s game as it looks like buses go halfway back to MG before Rheydt, or via Rheindahlen village with at least one change on both routes. I doubt the shuttle buses will be operating early for the U19s. The stadium itself is built on an old British Army base, Ayrshire barracks, so there's probably not a lot to do nearby when there's not a football match on, and I reckon the NAAFI shut years ago!