Moderators of child forums
 

Is there a mod (for 3.7.1 pl1) that can prevent a moderator of a parent forum from also moderating the child forums?

For example,
Jen is moderator of "News & Entertainment". The Book Club is a child forum of News & Entertainment, so she is automatically given moderator powers over that section as well.

Is there a mod that can prevent that from happening?

Try going into the forum moderators and taking away from there, if it's an option

It's not. They are listed there by default from the main forum pages, but if you look at the moderator assignments in the admincp, they are not actually assigned to the child forums.