After having discovered Rolf's corpse in the murloc village, run down to the bridge between Goldshire and the Eastvale Logging Camp and speak with Guard Thomas. This will finish the quest and lead to the next step, .
Now that you have both medallions, deliver them to Guard Thomas at the bridge so that he might know the fate of his murdered guards.
Hello, <name>. Have you discovered the fates of Rolf and Malakai?
You have confirmed my fears, <name>. The murlocs are a threat we cannot ignore.