You can do a quick search for Antivirus in most of the online shopping ecoomerce portals of Nepal – however they provide a summary of available antivirus software in Nepal.
You can check Kaspersky antivirus 3 user license for Rs 1,400 only.
Baleoyo (Sagar Group nepal) is authorized Kaspersky solutions and products seller for Nepal, check their product site http://www.baleyo.com/products.html?limit=11&manufacturer=140
Norton antivirus is also available in Nepal, Neoteric Nepal is its authorized reseller. You can find Norton 360, Norton Internet Security and Norton Antivirus in Nepal.