Triple Drop Down

Both your AJAX methods load the same view that was initially loaded for displaying the page:

PHP Code:

$this->load->view('cascadeDrop',$data); 


That's not the way to add or manipulate content on a page without a complete page refresh.
The AJAX method must echo the new output you need. In your case, just the (html) contents of a dropdown for selecting a state or city.
Try to build this html inside the controller first. If needed, you can put it in a view, and load it like this:

PHP Code:

echo $this->load->view('dropdown_cities',$data,TRUE);  //the 3rd parameter (TRUE) will return the output as a string. 


This will return only the html code for one of the dependent dropdowns.