Mother's maiden name

[tmmet]

Hi,
I used my mother's first name for "Mother's Maiden Name" in all forms that I filled in for Greencard.
I got my greencard.
I came to know that I have to use my mother's last name before her marriage for "Mother's maiden name".
So, I went to SSN office and filled out a form to change the same.
My question is will I have to use my new mother's maiden name or my old mother's maiden name while filing for Citizenship.I am confused now whether INS will verify my greencard documents or my ssn forms.
Any suggestions would be very helpful for me.

Thanks,