They said they were worried and tried to explain to her that Draco Malfoy was not a good person at all. Ron had told her about what he did to him during their school years, as well as what he had done when he became a Death Eater and Voldemort had tasked him with killing Dumbledore. He avoided to describe what had happened during the Horcrux hunt out of respect for Hermione, who was just observing her daughter in an unusual silence.