B.Com

CA is the best option but it requires a lot of time and focused hard work.

No doubt, CA is far better but success rate in CA is very low.

Yes, you are eligible for B.Ed.

You have scored 90%, which means you are a good scholar. Be confident and prepare well for CA. It will be the best.

Yes, you can apply in IGNOU at this age also.

Yes, you can enroll without maths if the same is not mentioned.

I would suggest you to grab some computer accounting skills like CFA and tally with GST, then get a job and work for at least a year and with that work experience get admission in M.Com.

Yes, you can pursue B.Com after the completion of you PUC with a minimum of 50% and with no backlogs.

These are the top colleges:
Mewar Institute Of Management, Ghaziabad.
Institute of Management Education Group Of Colleges - [IME], Ghaziabad.
Vidyavati Mukand Lal Girls College, Ghaziabad.
Amity University, Noida.
Amity Centre for Elearning, Noida.
Amity College of Commerce & Finance - [ACCF], Noida.

Click the link below :
https://www.shiksha.com/college/loyola-college-lc-chennai-nungambakkam-1108/admission#admission