I'd advise against sending a child this young to Nepal.
Adults unaccustomed to Nepal's conditions have a difficult enough time despite precautions.
While a child may sleep through most of the trip, others could be very uncomfortable.
Children anticipating travel to Nepal should have had the recommended inocculations prior to departure, sleep under mosquito netting, and be carefully monitored.
Certain afflictions could leave a child this young dead within 24 hours.
Meningitis, hepatitis, TB, malaria and giardia are some of the more prevelant and/or lethal ones.
During a short visit, one child of 3 had severe diarhea, bleeding, weight loss, went undiagnosed and came close to loosing his life.
This despite having received most of the suggested vaccinations.
Somel recommended vaccinations may not be easily available here.
Private practioners in Ktm provide them but ideally, they should be taken over several weeks and completed prior to departure.
Upon return, it would be wise to be tested and treated for parasites.
For travel abroad, the guardian would need to demonstrate both parents' authorization.
Perhaps your airline/travel agent could provide you with some advice.