She wasn't entirely sure how she managed it, but at some point in the long night, Hermione was able to fall asleep in the unfamiliar bed. Augustus was an intelligent enough man to understand that the last thing she wanted from him that night was him to follow her and still not answer her questions. He remained in his own bedroom to stew in his own frustrations. Eventually, the exhaustion from the waiting around for his return overruled her desire to stay awake and be angry.