Force a Player out of bed on a certain night?
Solution 1:
You don't actually have to kill the player to push him out of his bed. All you need to do is damage him.
/effect @p 19 2
That will deal half a heart of damage to the player, by poisoning him briefly, in order to wake him up.
Solution 2:
As of Minecraft 1.13.1, it is now possible to simply /tp the player to be not touching the bed, whereupon they will stop sleeping.