This one is actually about 8 - 12 months old. I just never found a good time to answer it.
How did the guys clean up the zombie arc? Simple. By destroying each and every single one. Most of them don't have to worry about being eaten, since they're already dead, and they're all perfectly welcome to vent the frustrations of life (and afterlife) on the zombies. It was stress relief. Eventually, there were no more extraneous dead wandering about.
What caused the zombie pseudo-apocalypse? Who knows? They certainly don't. But whatever did... may still be roaming around out there...
Erik belongs to Leroux and Webber.
Jareth belongs to Henson, Lucas, and Bowie.
Norrington belongs to Disney, Bruckheimer, and Davenport.
Javert belongs to Hugo, Boublil, Schonberg, and Kretzmer.