Display Field Collection items as select list in other content type
This is a partial answer, looking for further guidance!

After a lot of exploration, I still couldn't find exact solution to my question.

While searching I found this topic titled: Entity Reference view to populate select list for reference field => only one result when using a contextual filter, might help others. This is a long node addressing similar problem. 

But my problem was not solved by above mentioned link. So I used hook_form_alter,

function module_form_alter(&amp;$form, &amp;$form_state, $form_id){
    if($form_id == 'your_form_id'){
        $url_arg=arg(); //get arguments from URL
        $node_id=$url_arg[1];
        $node=node_load($node_id); //load appropriate node of Content type A
        $info = field_info_field('field_testing_code'); //load field from Content Type B's form
        $values = &amp;$info['settings']['allowed_values']; //get list of allowed values
        $values= array(); //remove all existing values
        $i=0;
        while($node-&gt;field_consignment_text_field[und][$i][value]){
            $values[$node-&gt;field_consignment_text_field[und][$i][value]] = $node-&gt;field_consignment_text_field[und][$i][value];
            $i++;
        }
    field_update_field($info);
  }
}


As I mentioned, each B content type is a sub part of A content type. And URL contains id of A. When I open content type B's creation form one at a time, it works fine. When I open more that one forms having different A parent, form_alter shuffles data e.g Field data of tab 1 gets assigned to tab 2.This is the issue now.
Looking for some solution for this.