Unfortunately, the bulk user actions page is not pluggable so you can't add local options like this without hacking core code. I would strongly recommend that you do not hack core code.
I would approach this by writing an 'admin report' plugin. It's highly unlikely that you'll find something to do what you want.
Existing reports are here - https://moodle.org/plugins/browse.php?list=category&id=4 - you may find something to give you a start.