ひどいことを言って、彼女を___しまった。
Q. Which form means 'made her cry'?
Translation
I said something terrible and made her cry.
Explanation
泣かせる is the causative 'make someone cry', taking the person as object: 彼女を泣かせてしまった. 泣かれる is passive ('have someone cry on you'), which would take に, not を.