Is return ticket needed to enter India?
 

Yes, although I know a few of my friends (with Indian Origin) who were not asked for a return ticket when travelling to India on a Tourist / entry visa but in my case (through Malaysia airlines) the staff at Melbourne airport did not allow for check in and boarding pass issued until I bought a return ticket to my daughter (Australian). I could not wait to get the OCI (life long visa) hence was travelling on an entry visa with only 1 way ticket as were not sure about return date. However, we had all the plans to handover the documents (for already online submitted OCI application) just a day after reaching India, I showed them all the proofs but no luck. If you want to stop getting stressed at airport I suggest be prepared.

Wade through the IATA Timatic visa data base and you'll see you generally need a return ticket but there are exceptions. Big one is holding a multiple-entry visa issued for a year or more. This makes most Americans exempt.

And airlines do sometimes make a fuss. I had great problems with AirAsia a few months ago.

If you are NRIs or non-indian residents, it is required to have return flight ticket as a proof. For Multiple-entry visa, I am not sure whether it is required.