There are no active volcanoes in Nepal. It has huge mountains, to be sure, but only a small percentage of mountains are built by volcanoes. Mountain-building events are most commonly triggered by tectonic plate collisions, which may or may not include vulcanism. Tectonic plate collisions are the cause of many, many earthquakes. However, relatively few nasty earthquakes are triggered by volcanoes. The nearest volcanic activity to Katmandu is a thousand kilometres northwest, in western China, where an eruption last occurred over 60 years ago. The action in far western China has produced a few cones, but no volcanic mountains.
There are none. Which is interesting, because usually we see volcanoes at tectonic plate collision zones, which the Himalayas are – the Indian subcontinent (sub meaning small) collides with the Asian supercontinent (super meaning big). However, in this case, you have continental (dry) rocks colliding with more continental (dry) rocks – and in the absence of water (most subducting plates are ocean floor, with plenty of ocean water soaking through them) we don’t get melting – so the result of that is: no volcanoes, just earthquakes