Yes, you should mail the tax return. E-filing again will just produce the same error. On a side note - is there a reason your parents are filing a tax return at all? They are probably not required to. If they are filing to get back anything that was withheld, they could contact whoever is withholding the tax and tell them not to. If you and your brother are going to continue to claim them, it would be easier if they did not file if they don't have to.
