"Discovery that a person failed to comply with any of the requirements for naturalization at the time the person became a U.S. citizen renders his or her naturalization illegally procured. This applies even if the person is innocent of any willful deception or misrepresentation. [2]"
https://www.uscis.gov/policy-m....anual/volume-12-part - She both can and must indeed be SENT BACK.