Adding “Unblock the user” option in Views Bulk Operations field
In drupal 7-

We need a Rules module, after enable Rules module and Rules UI go to

1- Configuration -> Workflow-> Rules-> Component-> Add Component

In Component plugin dropdown-> select Action Set
then add next page 
Fill the mandatory field Name as (Ex: Unblock user)

2- Select Data type from list User ---Label Unblock user ---machine name unblock_user -- usage parameter 

3- In setting option you can set Permission roles wise.

then click on continue button
then click on Add Action Link 

4- then Select the action to add User ->Unblock User

5- Select Data Selector -> unblock-user and Save

6- Now go to- Views Page add field Bulk operations there will be present Unblock user option

for reference - Add Unblock user option by rules in views and set permission