For your trip, you are recommended to convert the necessary cash into local or other acceptable currencies. As the exchange rate on the mountain may be expensive, you should convert the necessary cash at Kathmandu. Also, there aren't reliable ATM services available in the region. So if you are planning to use a credit card on the mountain, it may not be feasible.
That’s why you should consider properly budgeting for the trip and bringing a sufficient amount of cash with you. To check out the ongoing exchange rate in Nepal, you can check out the official section of the Nepal Rastra Bank’s exchange rate.