Hey Vikas, one of the best route to reach Nepal from Indore is via Bhopal, Jhansi, Kanpur and finally reaching Gorakhpur (gateway to enter Nepal). You can plan your road trip with the help of following travel itineraries.
Indore. Bhopal. Sanchi. Gyaraspur. Sagar (not a tourist place). Khajuraho. Ajaigarh. Allahabad. Varanasi. (option or there is a direct route to Faizabad) Faizabad. Kapilvastu. Lumbini (Nepal) from here U can move to Kathmandu or other places in Nepal.