MIL's purpose for being at the airport could have been to give her D support, so she (your W) would not cave to any emotion upon seeing you. Some mothers have extreme influence in their daughter's life. There's no telling how long she may have been working on her. Of course, this is me mind reading.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!
