Best way to manage multiple users on mobile dashboard

I am designing a mobile dashboard which needs to allow the admin user to manage anything from 20 - 100 sub users.

For each of the sub users, there are multiple possible actions EG: pay bill, analyse bill, update log in details, ETC. The actions could easily span too many categories to be on one page.

Would it be best to get the admin user to select the sub user in question and proceed from there as a top level task, and then select from a task, or choose the task first, and then the user.

If the task is chosen first, this means the admin user would have to sort though many users for nearly every single task on the dashboard.

I have tried to find mobile apps dealing with multiple users for inspiration but am struggling to find any as of yet.