Ashok, PhD ideally takes 4yrs and in some cases more yrs to get. If you want to have a career in research, then PhD is ideally the next step. However, if you get an RA position with your MSc degree and you stick to it you can still be promoted in the ranks.But then years of experience required is much more than with a phD.
Know your pros and cons, your definite aim in life (MBA, teaching, research, etc.), see what is required to acheive that goal, its impact on your family life, decide accordingly.
Good luck!