How could the Nepalese monarchy survive? Preventing the 2001 massacre is a must, but at that point Nepal was also dealing with a Maoist insurgency, and the country's development had been lagging for a long time.

The country was moving towards parliamentary democracy in the late 50's, but King Mahendra suspended the constitution in 1960 after couping the government and introduced the highly unpopular Panchayat system of royal governance. Stopping this is likely a good idea, as it would make Nepal more developed and secure than if we "simply" stop the massacre (there's still the Maoist uprising in that case).

I've dug into this and we have some options:
  • Kunwar Singh attempted to remove the king from power before the Panchayat regime in 1957, using the help of the army; however, general Nar Shamsher was loyal to the king and stopped the coup.

  • The more radical option is in 1962, when Durgananda Jha and his allies attempted to assassinate Mahendra by lobbing a bomb at him. They failed; Jha was hanged and his co-conspirators received the life sentence.
Which of these is the better option? Actally, are any of them better than leaving Nepal per OTL and instead stopping the royal massacre in 2001?

Would present-day Nepal be a fully parliamentary monarchy, like Japan and Britain? Or would it be an executive monarchy where the King holds genuine political power and rules along with a democratic government, like Bhutan and Morocco?

Maybe Tribhuvan could live longer? IOTL he died in 1955 age 48, whereafter Mahendra took over and dismantled democracy. Tribhuvan's cause of death seems unspecified, and I've seen things going from a heart attack to a cardiovascular disease. If Tribhuvan manages to live until, say, 1980, and dies age 74, could the Nepalese democracy remain in place?