Advantage (imidaclopride) is bunny safe and will kill fleas. I know some people use Advantix (imidaclopride + permethrin) on bunnies – but permethrin isn’t alltogether considered bunny safe.
As for the scab, monitor it and keep it clean. Some animals and humans get local allergic reactions to flea bites, but then again, any flea bites will itch because that’s what flea bites do.
Do NOT use any compound containing fipronil (Frontline, effipro, Sentry and more) on or near Bob. Not that you would, but it’s such a commonly used anti-parasitic so we always issue this warning. Fipronil is deadly toxic to rabbits.
You should also try and clean out your home (well, obviously). Diatomaceous earth can be used on carpets, along baseboards etc. It’s non-toxic but the bunny shouldn’t eat it or breathe a lot of it in directly, because it is a very fine powder and can mess with the tummy and/or the lungs.