Create Relation between two vocabulary terms in views expose filter
I am posting answer to this question, as it might help somebody.
I havent got any suitable module which can create relation between two taxonomy vocabularies as i want, But i have modified my taxonomy a little bit to do this from a module.

I have merged my 2 vocabularies into single . I have placed country as parent term and all the cities as sub-term. So my structure is like this :

India


Delhi
Rajashtan
Chandigarh
Gujrat


USA


Alabama
Alaska
Georgia
Illinois


Then I have used a simple module called "Simple Hierarchical Select" https://drupal.org/project/shs or you can also use Hierarchical Select" https://drupal.org/project/hierarchical_select 
But hierarchical select has more functions but if you have taxonomy related task only then you can use only SHS as in my case.

Now go to the content type -> manage fields -> select term reference-> simple hierarchical select .

Now go to your views => select the "your-field-name" (hierarchical select ) from filters
and force it to some depth.

Then it will show first country name and then child term which are city names.