They say: "O.K. We will grant your wish! We warned you! Goodbye!"
You blink, and suddenly, you're all alone in the room. Some sense of calm comes over you. The entire atmosphere of the place has changed: as if a million violent hearts suddenly realized the value of living. Suddenly, the entire house feels inviting, even warm.
You wander around the halls and grounds of the house without incident, meeting only friendly creatures and newcomers to the house as lost as yourself, all sharing the bounty this peace wrought. You try exiting the house every which way, failing every time. In fact, you start forgetting where you are, and wonder what your family and friends are up to on the outside world. One day, a newspaper blows into the backyard: "Six years since world peace declared!" reads the headline. You look around for a single soul outside the house, but none can be seen.
Eventually, you resign yourself to the fate of sharing a creaky musty old house with several formerly-scary beings, and start hosting dinner parties for your benefactors, toasting to shared values and anniversaries.
Another day, decades later, you find yourself sitting in the backyard, watching a full moon, a werewolf by your side. You wonder: how did I get here? and share the celebration of the moon with your friend by howling. A tear rolls down your cheek, as you remember the life you had before. Someday soon, you know, you'll pass away into the night, having saved countless lives at the cost of the rest of your own.
You failed to escape the house, but you also caused lasting world peace, and lived in a large house rent-free for decades. So... Congratulations?