A lawyer would be helpful in reviewing the criminal record to determine if in fact the USCIS properly applied the law, and, if so, an attorney could guide you through the waiver process:
A waiver under this provision is in the “sole and unreviewable discretion” of the Department of Homeland Security upon a determination that the “petitioner poses no risk to the beneficiary.”
She'll need a waiver, and, assuming she's granted a visa by the embassy/consulate, she'll need to get married within 90 days of her entry into the United States. The waiver will have to be based on an extreme and unusual hardship (presumably to you). Call me if you want to discuss this in more detail.