Hi,
It depend upon on life style.
3 bed furnished cost approximately 10k
5 to 8 k for monthly living cost such as (groceries, fruit, net, tv bill etc)
School fee is bit high i don't have idea about indian schools any how you can consider 2k per month on safer side.
out if 40k you can save 20k approximately with normal life style, as you might know luxuries has no limits :P
and final note: HMC is good place to work,,,