I have a friend from Norway who is visiting the US for the first time next week.
She will be staying with me for a week before continuing to NYC and Boston.

When she arrives at ORD, she plans to rent a car from Hertz. As a foreign
visitor, what type insurance/waiver or any other extra coverage can she buy
from Hertz? I assume extra liability insurance and loss damage waiver
are essential? She has no rental car coverage on either of her credit cards.
(Visa and MC issued by Norwegian banks)

Thanks!