Who is telling you that she has turned downed trips due to finances? Ask her what's up with that?

DC is the one in college. If she wants to do these activities, she will let you know. It's her life, and it's up to her to decide which activities are "neat."
If there's something you feel strongly about her doing, like a semester abroad, an internship or something, focus your efforts on that. Only.

Put the money in an account she can access.

The alternative is she tries to save money by drinking at house parties every weekend.

My daughter sometimes won't ask for things because she feels she's asked for a lot already. Or she's asked for that specific thing too many times.

Is she complaining?

DC sounds like a freshman who would rather claim they don't have the money rather than they need to study more to keep up.

Give your kid an allowance while at college.

DC has turned down invitations to some neat activities claiming lack of money. We have told DC we’re happy to provide. DC never asks. Feel like DC isn’t getting the most out of college, turning down trips with new friends, etc. How would you approach this with DC?