He said to her, "May you succeed!"

The correct answer is C. He wished her success.

Option A is incorrect because he did not tell her that she might succeed. He wished her success.

Option B is incorrect because he did not pray to God that she may succeed. He wished her success.

Option D is incorrect because he did not say to her that she might succeed. He wished her success.

In this sentence, "May you succeed!" is a common way to express good wishes for someone's success. It is similar to saying "I hope you succeed" or "I wish you all the best."