Capital gain tax exemption

Here's the situation. My mother bought a flat in 1997 for around Five Lakhs & cash we paid around 10 lakhs. & at present after the redevelopment we sold it for 80 lakhs + Cash AED 5L in 2016. Out of that we have already re-invested for 30 lakhs on New Flat + cash payment of Rs.13,.00 lakhs. Now the most Tricky part   My mom Wants to give me the remaining amount which shall be around 39 Lakhs for me to buy a flat by Transferring to my Bank Account. Will the Transfer of amount in my NRO account attract Capital Gain Tax? What can be done to save Capital Gain tax or Exemption.   1. Whether Mummy can execute Gift deed and transfer the said amount in my Name so that  I Can purchase flat with the same amount?   2. If mummy is buying can my name is also included with a small amount of investment from my side and buy  Jointly   3.Whether she directly pay the amount on my behalf to the builder? .4 Is it compulsory to buy a second house with the remaning amount in joint name First name Being my mother.  I would really appreciate your Advice and Opinion in this   Warm regards Vinod