[MunchkinMan]

In the past, we've said that a once-and-done card, like Annihilation, gets returned, but its effects do not get reversed. Cards like one-shot Items that give bonuses to a side, or Monster Enhancers, once gone, would no longer provide bonuses to the Monster(s), but an annihilated Monster would not return because of Restraining Order.

However, Restraining Order is not limited to being played during combat (it says, "Play at any time," at the start), nor is the combat over, since anyone could still wander a Monster in, even the player in combat. Beyond that, the player's turn is not over, and therefore he could still play Restraining Order, in order to prevent further abuses at the hand of a single player for the remainder of the turn. So, neither A, nor B, are correct, but:

C) The Monster is removed from the game completely and placed back in the box for this game, the player who played Annihilation gets it back (because of Restraining Order), and combat continues if anyone wanders in a Monster for the player in combat to fight. Otherwise, the player's turn moves on to playing Items, other cards, and then Charity.