To add some additional thoughts (I work in a related area):
Brain tumours are graded using a different system from other cancers, so it is not the same as thinking about people with other types of cancer (ie this is not about metastasizing, which you might hear about with other kinds of Grade 4 cancer). A Grade 4 brain tumour is the most aggressive and cancerous type of brain tumour, and GBMs are well known for their extremely poor survival rate (5-10% at 5 years with an average of 12-18 months). Treatment options are limited.
A normal treatment pathway would involve surgery, chemotherapy and radiotherapy, assuming you were fit enough to do so, and lots of regular scans to follow up. You would definitely look to do this if there were residual tumour, otherwise they regrow at a fast pace.
It is also very unlikely you would be back to work after 10 days after a major neurosurgical intervention, regardless of whether a wig could cover anything up. Access to these tumours is a big undertaking for the majority of locations for these tumours. Many people also require treatment with steroids and this often changes how they might look.
Reasons this might not be what happened here - 1. the tumour turned out to be of a non-aggressive or less aggressive type when they looked at the cells after her surgery, unlikely but can happen - thus improving treatment required and her prognosis 2. people do lie about these things, for lots of reasons, some reasons for which you might have more sympathy than others.
From what you have said, it at least sounds like a very unusual situation and I understand why you feel the way you do - but it sounds like it might be hard to challenge directly.