As someone who strongly believed in that, she had tolerated those shrewish villagers for years without taking any action. She didn't want to be forced into doing what she didn't want to do.
The only people she had killed ever since she was reborn were those traffickers who abducted Hayes. After that, she had tried her best to solve problems amicably as possible.
However, coming face to face with these people, her rationality seemed to fly away. After seeing what happened to her mother, she got so irked, that she wanted to vent out all these frustrations and it so happened that Orson arrived.
Before seeing Orson's arrival, she had gotten into a huge argument with Bertha. She stopped by the Thomas manor to check on the old lady. And when the old lady saw her, she was triggered and started reacting.