Naturally this wasn't possible that they would not get attacked by the Monsters, everyone of them who will be incharge of watching over while the other people will be sleeping will also be in charge of attacking those.
Naturally if the situation became more dangerous the other people will also join them to attack those Monsters but until they could handle those Monster they will do that. So like this you can say around 3:00 a.m. when only Allen and venesa watching over their surrounding while everyone sleeping, they also encounter some Monsters previously that they already killed.
Naturally both of them did not use their full power even though Allen decided to use some spirit bullets at this time because he did not wanted to take that long to kill those Monsters. On the other hand this time Venessa also show some of her real power.