I don't know the specific reason, but I do remember reading about about the EWR-BOM flight with MX issues in BOM.
There is a thread around Delayed/Canceled International Flights
http://www.flyertalk.com/forum/unite...ts-2015-a.html
There is also a thread that shows the history of issues with your specific flight
http://www.flyertalk.com/forum/unite...ry-irrops.html