Don’t be confused if you want make career in management field the take admission in IIM doe MBA study and if you want to do government job then go for IAS exam but keep one thing in mind both option are not easy for both you have to enter entrance exam

For IIM MBA you have to give CAT exam

For IAS you have to write UPSC civil services exam

IAS good option if :

If you want to get a Higher Profile Job in Government Sector

If you want a Higher respect in Society

If you want to provide a Civil and Social service to People ,You have to choose IAS Officer

If your goal is to become a IAS Officer, You should choose IAS Option after your graduation :

MBA Good option
you have a lot of interest in Business .If you like Business Much and Interest on Management Sector ,You should choose MBA

If you have very well communication skills want to earn money and want to start any new companies etc. You have to choose MBA