Agree with above comments. In our environmet we disabled the option of adding exlusion by the clients. We exclude the files and folders only through SEPM.
To answer your question you can check the registry keys on the client machine for the user defined exceptions.
Go to this key, HKEY_LOCAL_MACHINE\SOFTWARE\Symantec\Symantec Endpoint Protection\AV\Exclusions and under that key check for client.