Are you sure you have the whole story here? If a citizen, the ban would not apply. My guess is instead, she's just a LONG time resident that kept renewing her green card. This happens a LOT...but it isn't citizenship. Thing is, if you're going to live somewhere more than a decade, and insist loyalty to that state, you need to become a citizen to prove it. Otherwise, your loyalty is questionable at a time of strife between nations. Not to say she isn't, but just illustrating the perception. Renewal is an easier road than citizenship, so I get why many do it, but we all knew this was part of his platform and was coming.
If she really IS a citizen though, then this is a complete failure on the part of those preventing her return, as they are NOT following the order.