In which year of the drought did Elijah return to Ahab?

Answer: Third year

In the third year, God told Elijah to present himself to Ahab.

“After a long time, in the third year of the drought, the word of the LORD came to Elijah: “Go and present yourself to Ahab, and I will send rain upon the face of the earth.””— 1 Kings 18:1 (BSB)