The correct answer is
C. to make peace.The idiom “bury the hatchet” means to end a quarrel or disagreement. It is often used in the context of two people who have been enemies for a long time but have finally decided to make peace.
Option A is incorrect because the sworn enemies are not trying to help each other. They are trying to make peace.
Option B is incorrect because the sworn enemies are not trying to avoid each other. They are trying to make peace.
Option D is incorrect because the sworn enemies are not trying to become partners. They are trying to make peace.