B.Ed

You have not written about the college for better response. However the eligibility criteria of DU's is given below for an idea. B.Ed. Eligibility criteria of DU : Candidates with at least 50% marks in aggregate either in Bachelors Degree and / or in the Masters Degree in Science / Social Science /Humanities/ Commerce or any other qualification equivalent thereto are eligible for admission to the programme. Here M.Sc. Economics is falling under Social Science as per Table-1 of B.Ed. Prospectus 2020. Admission criteria : Admission test
So from above you are eligible for B.Ed. If meeting the aggregate percentage of eligibility criteria.

Yes, you can get admission, but you have to give the entrance examination for the BHU and I think this year's examination process was over so please visit BHU's official website to get more information.

Hello Dear, Firstly you are eligible to take admission in B.E. D in any university and if you mention the University name then I can give more information.

I think you should take your commerce subjects combination in B.Ed.