Update Task Status and outcome - sharepoint Task List

Hi Community, 

I have a sharepoint List where Manager assigns task to someone, the task status will be work-in progress at creation.

When the person A gets email of task assigned to him linking back to the list , he/she CAN'T edit the other columns like due date but ONLY Change the Task Status - (Completed  or Denied ) 

Task Name                     Assign To         Task Status                    Due Date

Computer Repair            Person A        Work in progress                 Today 

How Can I achieve this OR will it be best to create two Lists (one for manager to assign task ) and assignee list  to update the status ??

Please any info/pointer will be highly appreciated. 

Cheers.