You don't need to do Grizzly tasks. Just go straight to the Demon Oak boss with your axe and kill the monster waves.
A good strategy is to go in a team of 5 and take turns to go in, create a tera wall just to the west next to the teleport and the team standing outside provides support attacking and healing. If more than 5, there are extra spots outside to the west.
Go back to Quests.