Lol, not a lot in Dudley.
There is the black country museum but that closes pretty early on in the day, much like the castle and zoo.
If I were in Dudley for the evenings I would probably head to Merry Hill shopping centre for an evening looking at some shopping and grabbing something to eat there. There’s an okay if expensive outdoor shop up the top that’s worth wasting half hour in as well.
The other evening I would probably catch a film at the Showcase at Castlegate. Again there are plenty of places to eat surrounding it as well.
If you’re limited to evenings there isn’t a lot more to do, to be honest, especially if you don’t have your bike and lights to head to Cannock for a night ride.