Western Union or Moneygram do not deposit to bank account. Use your bank account here in America to transfer the money to the bank account in Nepal.

I am very sure that Western Union and Moneygram will require you to present quite a few papers if you want to send 20k.

Couple of people have used Riya Money Tranfer but personally I'd go with Moneygram or Western Union since Nepali money transfer have stopped doing it for the moment.

Also New York area has Prabhu Money Transfer that seems to get high remarks.