In the granular permissions (for the user group) enable browsing for the root Nodes that you do what them to be able to see, and disable for those not to be seen. You also have to individually set all the other permissions you want on those too as I think they'll all be overwritten.
For example:
Browse Node enabled for: Home (all children inherit by default)
Browse Node disabled for: Page C, Page, D, Page E, Page F