Arriving from Nepal, no yellow fever certificate is required: WHO does not list Nepal as a transmission risk. It can still be demanded if you have been in a risk country shortly before arriving.
Driving on a Nepal license
Nepal is party to the and Malaysia to the 1949 Geneva Convention. They share none, so no treaty obliges Malaysia to recognize an International Driving Permit issued in Nepal.
Whether a permit is required alongside your national license is set by national road law, which we have not checked for this pair.
Malaysia Digital Arrival Card (MDAC) — The Immigration Department requires visitors to complete the Malaysia Digital Arrival Card (MDAC) at imigresen-online.imi.gov.my and to present their passports together with a complete MDAC to the Immigration Officer. The MDAC registration form says your trip must be within 3 days, including the date of submission. Canada's travel advice says the MDAC is free and warns against websites that charge fees for it. The UK government says you do not need to complete an arrival card if you are not passing through immigration.
No official source states a rule on: travel insurance.