Dear Mr Pradeep,
There is one way to recovery the money from that lady. You may not like the idea because it involves another legal battle. But if the amount of your decree is significant, it will be worth a try.
1. If you have filed execution petition in your case, withdraw it. If not filed, then don't file.
2. File a declaratory suit under Specific Relief Act, 1963 to declare the transfer of property by lady to her son as null and void for being in contravention of Section 53 of Transfer of Property 1882. Section 53 takes about fraudulent transfer. Make lady defendant 1 and her son defendant 2 to the declaratory suit.
3. When you file the suit then along with the suit also file Application under Order 39 for injunction, restraining the defendants from causing any further transfer of the property.
4. While your declaratory suit is going on and if you find any property to lady's name file execution and proceed.
5. Meanwhile if the declaratory suit is decreed in your favour then file execution in earlier case immediately and get the property attached and then sold.
Obviously there are remedies of appeal available to her. But then if it has to be fight, let it be a good one.
All the Best.
Regards
Shubham Bhardwaj (Advocate)