After escaping Herod's prison, to whose house did Peter go, where many were praying?

Answer: Mary the mother of John Mark

Peter went to the house of Mary the mother of John, also called Mark, where many people had gathered to pray.

“And when he had realized this, he went to the house of Mary the mother of John, also called Mark, where many people had gathered together and were praying.”— Acts 12:12 (BSB)