You can try making mock bookings online on the following airlines. Unfortunately, there is no direct flight from Delhi to Montreal.
1. Jet Airways to Toronto, then either Air Canada or Westjet to Montreal
2. Delhi to Montreal via Doha with Qatar Airways
3. Delhi to Montreal via Munich with Lufthansa
4. Delhi to Montreal via London with British Airways
5. Delhi to Montreal via Paris with Air France
6. Delhi to Montreal via Amsterdam with KLM
7. Delhi to Montreal via Amman with Royal Jordanian
8. Delhi to Montreal via Zurich with Swiss