They don't. Actually it's technically no one's responsibility--it's a pretty new problem and people didn't even realize ghosts were real until months after they started showing up, so...

My parents do some of it, they're professional ghost hunters. The thermos I have--they made it, and I just have it for emergencies.

Plus, there is the Guys in White, they're technically the official government branch for this kind of stuff. But they, uh, kind of suck.