Rose was actually surprised at this Master guy. No matter what it seemed he was determined to see his life out even surviving a dalek blast. So they had some work to do if they were going to find this Master and get him somewhere he couldn't hurt anyone. It would be difficult, but her father was the CEO of Torchwood in this universe. They will be able to find anyone that wasn't acting normally. "I would like to help find him. Its my fault that he was let out." She says taking responsibility. After all the bloke wouldn't have had the opportunity to take over someone if she hadn't opened the TARDIS doors.