Can I become an Investment banker with Arts stream without Maths? and with Arts stream with Eco and Maths?
Yes, for sure! See, once you get into a well reputed MBA programme in India or abroad, it will matter very less that what you studied in your past. You may not have a formal education in Mathematics, but being quick in Maths and Finance is a very basis prerequisite for IB, and you'll have to fulfil this in any case.
A good B school will give you enough exposure to this and you'll sail along the rest of your fellow students. All the best!