Someone needs to keep the entrance safe so they can't go both. In that, the falling darkness is an unexpected ally. It might make getting people out easier if the wolves and their riders switch to an easier target.

"Lend me your sword and go lead them up. When you get them to your teammates come back. We'll see if we need to continue guarding the entrance."

They've sent a lot of people out already. If the goblins don't see too well in the dark it might be possible for the rest of them to slip out unnoticed under cover of the night.