As a resource, I found this. Not sure if it's the same issue.
https://wordpress.org/support/topic/500-internal-server-error-wp-admin-only?replies=7
Not sure what you're referring to by "nulled", but a plugin conflict might do it. Easiest and simplest way to uninstall a plugin when your Wordpress site breaks is to find that plugin's folder and delete it out of the Wordpress plugins folder. You can always reinstall them later.
I suggest removing them one by one so you can figure out which one caused the issue.
MM_CASETEST seems to be dreamweaver, but that's just based off the below link
http://blog.timolthof.com/mm_casetest4291-dont-worry-its-dreamweaver/