I suggest you go for a Post Graduation in Economics as it will help you gain specialisation in your field and make you eligible for very promising jobs in sectors like banking, investment, political consulting, manufacturing, transportation, sales and marketing, stock markets, governmental undertakings, NPOs etc. A Master’s graduate starts his career with a pay scale of Rs 15k-30k a month and steadily can reach to 15Lacs a year after gaining work experience.
Whereas a career through ICMAI is also well rewarding because then you will be in high demand in PSUs, but the scope at practical level is limited. But PG in economics will be more relevant to your career as you already have a degree in economics. Hence you will be able to stick and grow in this particular field and go up the ladder in the real working world.
All the best with your choices. 🙂