Dont you think you are too worried ? She is just 40 years old. She should be able to navigate airports. And immigration offices are used to dealing with people who have problems speaking english. If you are too worried, Get a set of cards for her. The cards need common sentences both in nepali and english which she can present to people to try to communicate. like (i need to be taken to this flight to for my transit)l I cannot speak english. I can understand hindi ( most airports have Indians who work there. )
Also see the route, she will be taking either (ktm-hkg or del or some middle eastern nation) she can ask the someone flying with her to assist her in the first leg. After that it should not be any problem to reach the states. I would also have her carry a smart phone and teach her to connect to the wifi hotsopts. She can talk to you in viber or fb messenger,

Hope this suggestion works.