Which prophetess did Josiah consult?

Answer: Huldah

They went to speak to Huldah the prophetess.

“So Hilkiah the priest, Ahikam, Achbor, Shaphan, and Asaiah went and spoke to Huldah the prophetess, the wife of Shallum son of Tikvah, the son of Harhas, the keeper of the wardrobe. She lived in Jerusalem, in the Second District.”— 2 Kings 22:14 (BSB)