Of course, there will be ATMs and a method for exchanging currency in the Everest region. Both Lukla and Namche Bazaar have access to the banking system.
Past that point, finding ATMs and such will be problematic. So the suggestion will be to exchange your money in Kathmandu before arriving in the Everest region.
Along with this, a few businesses in Everest Regions accept the international currency, which depends upon the time and the season.