Mode: Apocalypse
Difficulty: Any
Random: Yes
As you progress through the game you will eventually get a "someone is scratching on the door" or "Someone is banging and trying to get in!".
This option will let you choose between weapons and a "peg lock" (the item in the achievement picture). Save that item ONLY for this (it's honestly only useful for this).
And once you click it and go to the next day your achievement will pop