My budget is ₹8 lakh and my family has five members. I am looking for the best family car within this budget, with rear-seat comfort being the top priority. Please suggest suitable options.

Given your requirements, the Nissan Magnite and Renault Kiger are worth a look. There's plenty of space for rear seat passengers, and there is enough room for three passengers to sit in the back in reasonable comfort. 

You could also consider the superbly packaged Renault Triber. It's three rows of seats give lots of flexibility in seating, and the option to slide the middle row also means you can open up lots of legroom by moving the seat to its rearward position.