Hiiii

MBC will fall under OBC category if your family income is less than 8 lakhs per annum(i.e. non-creamy layer) . Otherwise you will fall under General category(creamy layer).

You have to get the OBC certificate in a prescribed form from state authority (thashildar) by producing the pay slip of the family income.

So if you belong to MBC category then you have to select the option OCB( NCL) and provide the certificate for the same.
There is no issue in this.

Hope this helps.

Thanks!