Cat C is under cat B already.
Perhaps you misunderstand.
I need a page listing all categories under cat B, then when a user clicks one, they are directed to another page listing cat c categories. These navigational pages will display no content.
Think of it like this, Country -> State -> City
The country page would have all countries listed, user clicks, is presented with a page displaying a list of states, select a state then see a list of cities…. and finally user clicks a city and is able to view all posts under it.
Does this make sense? I am just trying to build category navigation system.