The sentence talks about an action that has been accomplished and so it requires an adverb of manner to convey this meaning of the verb. Adverbs of manner are used to tell us the way or how something is done. ‘Already’ can bring out the meaning of the action being accomplished. Hence, Option B is the correct answer. Options A, C and D cannot be used as not ‘ever’, ‘yet’ and ‘never’ would render the sentence meaningless.