[Solved] Assassins creep

In Assassins Creep there are some mob problems, like when it goes to night time the are hundreds of mobs, if i do /killall it kills most of them but they respawn straight away so its an endless battle, so to keep the creepers away at the moment i just keep doing /day so it never goes dark (except there are still some...) I was wondering is there a way to get rid of all mobs completely?
-Sam-