Happy to help if you still need this fixed.
Unless files have been deleted a back up should generally be avoided. Websites are often hacked for some time before becoming noticed, and there's no way to tell if a backup is clean. It's better to clean and identify the malicious files, and if possible plug the vulnerability that lead to the compromise.
Once everything has been cleaned and you're sure the malicious URL no longer exists the site will need to be submitted for a security review in Google's Search Console.


