The correct option is B vanity
The word 'modesty' refers to the quality of being unassuming in the estimation of one's abilities.
Option A, vanity refers to having excessive pride in one's own appearance and achievements.
Option B, superiority refers to the state of being superior.
Option C, hypocrisy refers to the practice of to have higher standards or more noble beliefs than is the case.
Option D, arrogance refers to the quality of being arrogant.
Thus, according to the meaning, the word 'vanity' is the opposite of the word 'modesty'.