Facebook account is hacked how do I get it back?

Alright. Get this. My mom's facebook was hacked. The email was changed to some weird *** email. She had this other email hooked up to it. So I went on her old email that was attached to the account, I found the email from Facebook about her password being changed, so I clicked on the link that basically said "I didn't request for my password to change" to which it asked for the code that was in the email. I entered in the exact code that was in the email. It said it wasn't the right code. I COPIED AND PASTED THE CODE HOW IS IT WRONG? So then my mom creates this gmail account to recover her facebook. THE HACKER SOMEHOW HACKED THAT GMAIL ACCOUNT!!!!!!!! They changed the password and the security question to "Who is your favorite white pussy?" and somehow that email got added to the facebook account and I think it's because my mom sent facebook her photo ID. And what is SO MUCH WORSE is that my mom didn't provide a backup email for if that email got hacked because Google didn't ask her first. So I created a new email and I made sure that I added my email as the backup. Now I'm trying to figure out how to get to the part in the recovery process on facebook where I type in the email connected to the facebook account, then provide the new email, and give them my mom's photo ID so that way we can access this Facebook. t. I wouldn't care so much if this account didn't have pictures of my dead sister on it when she was alive. I am so pissed off.