The journey from Muhamma to Guwahati is a massive 3200 km trip. You should travel to Alappuzha railway station to board a train. Most routes require a change at major hubs like Chennai or Kolkata. The total travel time is approximately 60 hours. Guwahati is the gateway to Northeast India.
Total Distance: 3200 km by road, 2600 km air distance.
This is a very long journey; consider breaking it up in Kolkata.
October to March for pleasant weather.