Best Advance Degree? Up and coming banker
 

So, since I happen to know this forum is full of intelligent people who like to help each other, can I get some advice for my 22 year old daughter?
She has a bachelors degree already in sociology but her first job out of college last year was in banking.
She was recently promoted from a teller to personal banker/teller and decided she likes it.
What should her next step be?
MBA
Finance
Certificate in investments ...
????

Thank you for your input!