The moral of the story is to lay aside feuds or arguments because they could lead down the path of destruction. Had Georg and Ulrich not been in the woods hunting each other in order to claim ownership of a worthless piece of land that their families had been feuding over for generations, they might not have met their fates with the wolves that night. Each man allowed this feud to consume him even though neither man really used this piece of land dividing their estates anyway. By the time the men were ready to lay aside their differences while trapped beneath the tree, it was already too late for their rescuers were not people, but a pack of wolves. The moral is to learn to compromise and resolve differences before they lead to the destruction of one's life.
If you want to know more about themes instead of morals like enmity (the ill feelings that the men felt toward one another), social class (the fact that the men came from different social statuses), or even man and nature (the fact that the men are felled by a tree and a pack of wolves), then check out the link below.
the theme of this story is to know that no use comes from petty quarrels.
the answer would be that the interlopers are wolves :O