My question is...if I will do MBA after bca and then I will do MCA ..then how many years it should take?
Yes like akshay i would also suggest you to go for MBA in IT. I provide link of UEM Jaipur which will give you a clear picture of how many years to take to complete the courses you choose https://engineering.careers360.com/colleges/university-of-engineering-and-management-jaipur
But honestly there is no point in doing MCA after MBA. NO ONE DO THIS. If you are interested in computer science and also in management then do MBA with specialization in IT stream from atop reputed college like IIM and end up getting a very good post in companies like Microsoft with a very high package.
Or if you are only interested in computer science then directly go for MCA and become an expert in that field.
After MBA doing MCA will be foolishness. Instead of MCA you can work for 3 years in IT company and reach to a very high senior post with a lot of learning in both ways knowledge and money.
But even after MBA you want to study then do FPM which is equivalent to PHD. You can pick up a subject related to your interest and do PHD, it will take up your 5 years.
Make a wide and sensible decision!!
MBA is a course of 2 years duration while MCA is course of 3 years duration(but in some colleges it is of 2 years like VIT).
So total you have to give 5 years to pursue mba and mca after bca.But i would suggest you to opt for only one course either in management or computer science.You should always go with your interest.
Good luck.