Filter task performers with same roles but different duties and permissions

I made a question before, But my question didn't understood well and answer didn't proper for my question. Let's make an example I have three users A,B,C with same role and each user belongs to A', B' , C' department and departments have same functionality and same tasks, I assigned their role to task and now when a task instantiates for department for example A', users B and C can see it too, I want each user just see tasks belongs to it self. how should I do that ?