score:8
She can enter even on the day it expires. US visas are for entry requests only and it is not a problem to use them on their last date.
Just for the sake of completion, she can then stay in the US for as long as the CBP stamp/record allows. Even beyond the expiry date of her visa.
What the Visa Expiration Date Means
The visa expiration date is shown on the visa along with the visa issuance date. The time between visa issuance and expiration date is called your visa validity. The visa validity is the length of time you are permitted to travel to a port-of-entry in the United States.
Source: travel.state.gov