The correct option is
B modern
The word 'ancient' refers to belonging to the very distant past and no longer in existence.
Option A, fresh refers to something new or different.
Option B, new refers to something not existing before.
Option C, recent refers to belonging to a past period comparatively close to the present.
Option D, modern refers to relating to the present or recent times as opposed to the remote past.
Option E, refreshed refers to having regained strength or energy.
Thus, according to the meaning, the word 'modern' is the opposite of the word 'ancient'.