I would double check whether the crime she was actually a arrested for a crime that, in the words of the ESTA form, that was either drug-related or resulted in "serious damage to property, or serious harm to another person or government authority". I would imagine if CBP previously decided to allow her in on ESTA after talking to her about it, the crime did not meet that definition.

If that's the case, her problem is not her arrest, but the fact that she made a mistake on ESTA form... a potentially very costly mistake.

I know it is possible in some cases to correct mistaken answers on the ESTA form by calling or emailing CBP - they can reset it so a subsequent application with the corrected answers will not be auto-denied, avoiding the need to apply for a visa.

However, I do not know if they will do that for a mistake on the crime question - the US might want to investigate her in more detail through the visa process, so they can decide themselves whether or not the crime fits the criteria. But it is worth contacting CBP, and telling them she made a mistake on the application, just to be sure.