So why isn't she applying for citizenship now?
"Otherwise Eligible Immediate Relatives
If "otherwise eligible" to immigrate to the U.S., immediate relatives may adjust status to LPR (get a "green card") in the United States even if they may have done any of the following:
* worked without permission,
* remained in the U.S. past the period of lawful admission (e.g., past the expiration date on your I-94) and filed for adjustment of status while in an unlawful status because of that,
* failed otherwise to maintain lawful status and with the proper immigration documentation, or
* have been admitted as a visitor without a visa under sections 212(l) or 217 of the Act (which are the 15-day admission under the Guam visa waiver program and the 90-day admission under the Visa Waiver Program, respectively). "
USCIS.gov