Greetings dear aspirant

No, you cannot obtain an EWS certificate. Economically Weaker Section (EWS) in India is a subcategory of people belonging to the General Category having an annual family income less than 8 lakhs and who absolutely do not belong to any category such as SC/ST/OBC. If a candidate who doesn't fall under castes recognised as SC/ST/OBC by the Govt, only those candidates are eligible to get an EWS certificate. Since, you are recognized as BC-B you cannot get an EWS certificate.

Hope this helps!!

All the best for your future career