Hi OP, sadly what you describe happening to your ex is actually extremely common. It's known as 13th-stepping so while it is possible that your ex is making it up for whatever reason (?), it's also very likely that what she has told you is happening is the truth.
The way the AA works is that each group is autonomous so someone can bring this up with the chair and he/she may be able to stop this from happening again but other than that there isn't anyone "official" who can deal with this. If it were me I'd attempt to find another meeting that these two men were not at. If that was not possible I'd find an alternative, perhaps get a private counsellor.
She is very unlikely to find any recovery in a meeting where she feels uncomfortable or threatened.