I don't know if I'm understanding you correctly, but that diagram doesn't show the derailleur hanger. On your bike, the hanger is built into the frame. On aluminum or carbon bikes, the hanger is a separate piece that attaches to the frame. In either case, the derailleur attaches with Part 1 on the diagram, labeled "B-Axle Assembly", and the large bolt screws into the hanger.
Are you asking whether that bolt is available separately? What's actually going on with your bike?