The correct answer is B. completely.
The phrase “beaten neck and crop” means “to be defeated completely and utterly.” In the context of the sentence, Sunil thought that his skill would be a match for Keshav’s bulk, but he was wrong. Keshav was much stronger than Sunil, and he defeated him easily.
The other options are incorrect because they do not accurately describe the meaning of the phrase “beaten neck and crop.” Option A, “softly,” does not convey the idea of defeat. Option C, “swiftly,” does not convey the idea of completeness. Option D, “profoundly,” does not convey the idea of defeat.