You can't expect miracles. This isn't a luxury van so you'll have to spend a bit. To get any noticeable difference in the cabin noise, you need to do 3 stages. 1 is sound deadeners ( sheets made of aluminum with butyl rubber adhesive ). 2nd is Mass loaded vinyl (mlv). This is much harder to get but desi versions are available. Originally the vinyl comes with a sticky bqck but the desi vinyl with have to be stuck on with glue. And finally it's the ccf ( closed cell foam ). Desi alternative is Lambda foam or Jumbolon.
Most of your cabin noise is from the floor and wheel arches + engine firewall. Lining the floor with these three layers is the best way to go. As for the doors ( both inner and outer layers ) you can opt for sound deadening sheets + ccf on the inner skin. Unless you can find the sticky mlv, the glue for the mlv won't last on vertical panels. Finally, you can also do sound deadening sheets on the roof + ccf
