Hermione didn’t say she was in the bathroom during the incident being referred to because she had been petrified by the Basilisk and thus could not speak or move.
What is the context of Hermione being in the bathroom?
Hermione was in the bathroom during her second year at Hogwarts when she discovered that someone had written a message on the wall in blood, which ultimately led her to uncover the mystery of the Chamber of Secrets.