This piece goes along with the other Viking Assassin painting. The idea is that in order to become a Master Assassin, you had to kill a wolf, or a bear, or another dangerous animal with only your hidden blade, and bring back certain parts of said animal to prove your rank. Those who killed more dangerous beasts received a higher rank, those who died went to Valhalla.
She chose to track, battle and kill an enormous bear, to prove that she is worthy of leading the Viking Assassin's.