Hello

Though any one (from any stream) can give this exam but you can gain an upper hand in MCS exam if you have these subjects in your graduation:

English

General knowledge

As your optional subject you can choose any of the following:

Agriculture

Botany

Chemistry

Economics

English

Geography

History etc. Out of all these according to me history will  be the best choice for MCS. Hence you should go for BA(Hons) in English or Histroy. All the best.