I looked up WashU for you - not sure where you got your numbers but this is what it says on their website for 2016-2017:
Tuition $48,950
Avg Room and Board $15,596 (based on double and silver meal plan)
Student Activity Fee $490
Student Health and Wellness Fee $330
Total Charges $66,916 (it doesn’t add up - it should be $65,366) (I figured out why - it says the difference is due to books and supplies!)
http://admissions.wustl.edu/scholarships-financial-aid/Pages/undergraduate-charges.aspx
Grant - $57,650. That means you’ll have to come up with around $7,716 excluding books/supplies.
As far as health insurance, does your family have health insurance? If so, you can opt out. I did that for my D.