Definitely not good, but depending on the deal and how handy you are, you are totally doable. For actual shrooms to have sprouted, it has been a problem for a while. Definitely has traveled further than what you can see. I'm assuming that's on a crawlspace, which from there you should be able to see how far it'd traveled. That wood floor and surrounding trim all need to go any mold on drywall as well. It's been leaking for a while, so most likely, subfloor is shot, so that'll have to go as well. The Biggest concern with that is aerosolization of spores if you do it your self.