Who killed Da Yuer's mother in Tears-Free Love between Mountains and Rivers?

She jumped off the building on purpose, so she committed suicide. She was talking to Hailanzhu on the tower, when she saw Da Yuer coming out, she jumped decisively. The purpose is to make her hate Hailanzhu and make her strong, because she knows that in the palace, the law of the jungle, only when she jumps, her and Hailanzhu will turn against each other, and at that time, she seems to have committed something, and she can't live, so she did.