I actually agree with pia here. Though her way of conveying it was not the best, they do need to leave. Leaving the village will hurt, but it won't kill them, thinking that leaving is death is too narrow minded. And the adventurers shouldn't be sacrificed to protect the fields.
At this point all they know is that they are facing unending waves from the dungeon with no support coming. Retreating is the only real option for them.