Your wife just needs to fill out the
frozen account form asking for more explanations on why she was frozen because she's never bought or sold NP (she may need to create a new account for this). Hopefully she'll hear from a member of TNT within the next week or two; she may need to answer their queries or correct misunderstandings, but as long as she's polite, responsive, and truly hasn't broken any rules, she has a good shot at getting her account returned to her.
I've heard that the process has only taken a week or two lately, so hopefully she'll be back in her account in no time. When it's returned, she can then either self-freeze her new account or use it as a side account (paying careful attention to follow all the rules about not earning NP on side accounts so she doesn't inadvertently get frozen again).
If she has trouble with the process, I'm sure if she poses more specific questions here, people who've been through the process can help her.