170.000?? How did she do that? For this ammount of money she could have founded her own business. Even at an interest rate of only 4% she would have to pay $ 6.800 for the interest each year. This means even if she could afford to pay every month $ 500 then the loan would still increase.
When she would pay $ 1000 per month for the next 20 years, then after 20 years there still would be a rest of nearly $ 20.000 to pay.
That's a tough situation. Many twentysomethigns are feeling so overwhelmed by their student loan debts, that they are living back at home with their parents in record number. So your situation is not unique
Can she consolidate? Maybe ask for a forebearance? This is a really unfortunate situation that's going to take a lot of discipline to get out of. Your daughter is literally going to have to pay off a mortgage-size debt. I hope she at least got a good job?