I would run them to the ground! I know at least one of the lines is a fuel over-flow line, and I believe the other was used to vent fumes to the canister.

Leaving the over-flow open risks liquid fuel pouring out if you over-fill the tank, and/or ride enough rough stuff to have fuel enter the over-flow circuit. Same goes for the vent line... fuel fumes exiting above the engine don’t give me a good feeling. I’d rather they go to the ground as well.