Undergrad score - 8.4/10
High School - 94 %
GMAT - 690 (V41,Q44)

Work ex - 3 years in a startup selling a SaaS product in US and Europe markets.

Extra curricular - Blogger with 3000 + followers, I've been learning to play the violin for 1 year, know stock markets inside out.

Targeting US B schools. Future career - I want to get into consulting preferably into Mergers and Acquisitions.

What are the B-schools in US I should consider applying to.

Check out the list of top schools for consulting here:

http://find-mba.com/lists/top-business-school-by-speciality/top-business-schools-for-consulting

Considering your work experience is on the law side, and especially if you're from an over-represented applicant group (from south Asia, for instance), you'll probably want to boost your GMAT score and at least break 700. The average GMAT at MIT is usually 715 or so, at Booth it's more like 720+.

You'll want a high enough GMAT score to help offset your lower than average work experience. Something like Emory might be a safety school.