Assume the worst case scenario, which is your entire hosting account is compromised (all websites under your hosting account) and do the steps in this forum topic to clean up your hacked hosting account: https://forum.ait-pro.com/forums/topic/wordpress-hacked-wordpress-hack-cleanup-wordpress-hack-repair/
Note: It is very important that you do the cleanup steps in order in the forum link above for these reasons: If someone has cracked or stolen your FTP or hosting account passwords then you will end up redoing all of your cleanup again since the hacker already owns your entire hosting account.
It is also very important that all of your sites are offline while you are doing the cleanup and changing passwords AND very important that you make a backup of everything before putting your sites back online. The reason for that is you may have a plugin or theme installed that is allowing the hacker to control your entire hosting account. Example: If you have a plugin or theme with an upload form and that upload form is allowing a hacker to upload hacker files to your hosting account then BPS will not interfere or block the exploitable upload form because that form appears to be part of the normal functionality of that plugin or theme. BPS does not interere with or block the normal functionality of plugins and themes.
So if you have a good clean backup before putting your sites back online then if you do have a plugin or theme installed that is the root cause of the hack and your sites get hacked again you can quickly restore everything. If this does occur then you need to find the plugin or theme that is the source of the hack.
Also be sure to notify your web host about your website being hacked so that they can check their/your hosting server to make sure it is not the source of the hack. Example: A hacker finds an exploitable vulnerability on your host server. The hacker would be able to hack all websites on that host server by exploiting/hacking the host server itself. Your host needs to be notified so that they can rule out the possibility that the host server itself was hacked.