Hi DGUPTA9,
It doesn't appear that the Run Excel Macro command has a return value output parameter just like the Run Script command.
So may be you could try running the macro from a script file (like vbs) and see what happens.
An approach to this could be that you run the macro from AA and have the macro store the result in some far away hidden cell like Column Z and then read that cell from AA and get the result in a variable.