Which two of Dinah's brothers killed every male in the city of Shechem?

Answer: Simeon and Levi

Three days after the men were circumcised, while they were still in pain, Simeon and Levi took their swords and killed every male.

“Three days later, while they were still in pain, two of Jacob’s sons (Dinah’s brothers Simeon and Levi) took their swords, went into the unsuspecting city, and slaughtered every male.”— Genesis 34:25 (BSB)