Both of Li Du's parents were up against Old Lady Cao. It was two of them arguing against her so she was at her wit's end.
On top of that, the old lady only ever used the same few lines when she was scolding someone. It was the regular few — about men and women's genitals or the mental health of the other party's family. These were the basic ones everyone used in an argument and the Lis had long built up a resistance against these trite insults.
Li Du's mother, on the other hand, had a technique. She knew about the Cao family and where to strike for it to hurt the most, so she targeted their sore spots and launched into an aggressive rebuke. This method was much more vicious.
Old Lady Cao was so angry she almost blew up. In the end, she could not hold her anger in anymore and rolled her sleeves up, preparing to swing.
