It doesn't have to be a 1, 2, or 3 decision. Cash savings for a down payment and savings for student loans is the same thing, so let's say the decision is between saving cash for planned expenses vs investing for long term growth. The first thing I would do is figure out how much you need for a down payment. That would be my cash savings goal. Anything else would be going into retirement accounts.
When your gf gets a job, she can easily pay off her student loan balance in less than 6 months. At that rate, the interest is negligible. Also, not saving cash for the loans allows that money to be invested and potentially return more than the interest rate of her loans. So IMO plan on having her pay off her own loans with the new job.