Car purchase… seller passed away

HI am new here and didn’t know where I could put this post so a well-known one of me bought a car (private purchase) which had fresh tuv now he had but strange noises while driving and there he drove back to the tuv and there were faults found by the seller said he would fix it but he has now passed away. my well-known now wants the money back. But the friend(not married) of the seller said she didn’t have the money and would it him also don’t give because she doesn’t have to deal with it and he should please pick up his car my question to you he can do what he gets his money back or does he now have to be??