Lice advice!

So my 11 year old niece just spent the night the other night and I woke up to a text from my mom letting me know they just discovered that she has lice. They are starting to treat her hair and I'm not letting her come over for a while. I know she didn't pick it up from my house but I'm now in panic mode trying to do everything I can to prevent an outbreak at my house! As I am the only female in my house right now taking care of my boys if they get lice is fairly simple, I can shave their heads. But I dont want it to come to that. So I'm already washing and bagging bedding and all that fun stuff. We use tea tree oil shampoo already so I'm glad for that. PLEASE throw at me ANYTHING AND EVERYTHING that you know to help my situation before it becomes a situation! Thank you sooo much!!!!!