Can i go for a Phd after my PGDBM if no then advise me how to go about it. i would love to enroll myself for a Phd in USA

We're not sure if your postgraduate diploma will be suffiecient. We would expect that you would need to enrol on a Masters degree programme in the USA.

can i get a scholarship for masters programme and what is the score required for scholarship

Many USA universities do offer scholarships for exceptional candidates. The Fulbright Commission in India will have information on scholarships, qualifications and application procedures.