Along with BulletProof, Wordfence is one of the highest rated, and most used security plugins for WordPress.
However her hacking issue was likely the cause of a security vulnerability in one of her WordPress plugins. We often see this with clients that do not update their plugins, or have plugins that haven't had updates in ages. Some plugins are created as a front solely to steal data or have another security vulnerability.
One of the best ways to combat this is to #1. Make sure you update your plugins regularly and #2. Only download plugins that are highly rated and are updated regularly.
