What Serbs has to do with Dalmatia? It's Croat/ Italian beef; how Serbs came into you mind remains absolute mystery to me.
Vojvodina was always multiethnic land and expelled, killed etc. Hungarians were the ones who cooperated with Nazis during WW2, but it wasn't strictly applied to them but also local quislings no matter their ethnicity and such a decision was made by late President Josip Broz Tito, an ethnic Croat. You should definitely go over history books one more time.