You have to reduce the moral of a Timberwolf hunt to 0.
This can be done in either Wintermute (episode 3 and 4) or Survival (only in Bleak Inlet, Sundered Pass and Blackrock)
This is easiest in episode 3 in wintermute mode as they are the main "antagonist" in that episode and you're given plenty of marine flares to deal with them.
In survival it's best to stock up on marine flares and/or have a flare gun with ammunition. Go to either Bleak Inlet, Sundered Pass or Blackrock, get into timberwolf hunt and either that throwing marine flares at the wolves or firing the flair gun at them to reduce their moral.
Guns are another option to reduce moral by firing at them and killing them off one by one.