I think scratch will follow Saul, Victor, Lizzy, Puck, and Karl back to Dunbar. We hear how gridlocked everything seems to be around LA so there wouldn't be many ways to go from the Colony to Dunbar. Scratch doesn't know exactly where Dunbar is but they know it's approximate lactation so a probable route could be figured out depending on gridlocks and the area where they know it could be.

Scratch tries to get Saul and Victor to break her into the Colony and are forced to tell Lizzy they were exiled.