Roles / Users etc confusion

So i move up and down left and right through the catalogue of all the WP plugins in search for something that can do the following:
Assign anew USER and give this user no (0) other Admin option than 1 single Blog Category. This Users Admin panel will not have what a regular say Author will see, no “Media” etc., just a specific category within the Blog POSTS.

Now looking through the various role, access, users, and what they are all called manager plugins i only get confused because i really don’t know the destinctio or often i don’t understand the description, so i thought i try to explain here what exactly i need (as above) and ask if anyone knows which plugin/s will be able to let me assign such a User capability / role, i don’t know what it’s really called….

Thanks for any tips…