Which title is correct

You don't provide us with enoungh context to decide which is correct -- both, as well as Evening Program, could be correct under different circumstances.

The evening program will begin at eight o'clock. (adjective use of evening)

This evening's program will feature a piano solo. (possessive use of evening)

Evenings (the plural) is less likely to be correct in the context of program (singular). The following is more likely:

The evening programs will all be on a Tuesday.

I hope this helps.