The journey from Malappuram to Patna covers 2500 km. The most practical way is to take a train to a major junction like Chennai or Kolkata and then a connecting train to Patna. Alternatively, flying is recommended due to the extreme distance. Patna is a historic city on the banks of the Ganges.
Total Distance: 2500 km by road and 2000 km air distance.
This is a very long journey; consider breaking it up.
October to March for pleasant weather.