The 49-year-old and her daughter were returning from a trip to Everest base camp, located at 5,364 metres, when she experienced trouble breathing and stopped for a night at a hotel in Khumjung, en route to the capital Kathmandu.
"She possibly died of altitude sickness," local police official, Purushottam Silwal, told AFP.
"Her body was airlifted to Kathmandu for a post-mortem," Silwal said.
Altitude sickness strikes when people ascend heights too quickly, as the decreased atmosphere pressure causes headaches, fatigue and dizziness.
October is peak trekking season in the Himalayan nation, which is home to eight of the world's 14 highest mountains.
Hundreds of climbers abandoned plans to ascend Mount Everest in April this year after 16 Nepalese guides were killed in an avalanche, marking the deadliest day on the 8,848-metre peak.