How to Extract Label of a Field, which is inside FieldCollection? I have a field collection with the name 'field_stk_fld1'.

Inside this field collection('field_stk_fld1') there is a field with name 'field_fld_stk_ques1'.

I wanted to extract label of the field ('field_fld_stk_ques1'), Any idea on how to get it?

Note: This field ('field_fld_stk_ques1') is used in multiple places and in each place it has its own label associated.
This should do it:

$entity_type = 'field_collection_item';
$bundle_name = 'field_some_field'; // Field name the collection is attached to
$field_name = 'field_some_other_field'; // Field name within the field collection

$info = field_info_instance($entity_type, $field_name, $bundle_name);

if ($info) {
  $label = $info['label'];
}