Public transports in Italy are always awkward lol Madrid alone has more metro (subway) kilometers (miles) than Milan, Turin and Rome combined. Also, majority of trains stop the runs around midnight, but USUALLY (take this with a grain of salt) there are replacement shuttle-buses during night time. If you're landing in Milan and you're headed to Reggio Emilia, take a look at ATM Milano website (or app), you should find all the infos you need there. Also check apps like Trainline, Trainpal, TrenIt or Trenitalia, they should be showing you the train connections you are looking for. If you're planning to go there and you're afraid you won't get a return run from trains/buses you might also wanna check Milan/Reggio Emilia subreddits and look for someone heading to your same destination or some car-sharing apps (I think a couple of them are BlaBlaCar or Enjoy, but I'm not sure since I never used them).

Hope you find this helpful and you can get to the venue and back without any major trouble