Mostly what bothered her was Corban's reaction to hearing what she said about the tragic incident with the stairs. The wizard was furious that she would suggest Antonin was somehow responsible for her fall. Why? It couldn't have been a secret to their closest neighbors that their home was often filled with violence. Between the shouting they must have been able to hear and the fact that Hermione knew for a fact that Ollie snuck out a few times in the midst of their biggest rows to seek refuge with Mafalda, there was simply no way that the Yaxleys didn't know what was happening next door. Why would Corban act as if she was delusional and making it all up in her head? She wasn't that confused.