If it's the streets that interest you [and more so since your itinerary mention only 3 cities], B&W is fine. But if your interest covers other stuff as well, colour would be your best pal. However, as someone earlier said that the focus of your attention shifts the moment you switch between colour and B&W, you will have to take a call accordingly.
And by the way, pack as much film as possible since the chances of getting the films of your choice is almost zero in most photography stores here. If you need any help, please feel free to PM me - have stayed in Delhi + Bangalore for the last 18 years and so may be able to offer some help.

Have a great time here.

Cheers
Deb