Vacation while on B2

[jokos]

I am here on a J-1 visa. My girlfriend just got her B2 visa approved at the embassy in Norway (3 months Visa). We have planned, booked plane tickets and a hotel in Bahamas 4 days after she arrives in the US. The vacation is for one week.
I don't know if she will get a single or multiple entry visa yet. Will she have trouble re-entering the US after this trip?

[immihelp]

She needs to have multiple entry visa if she wants to enter the US again.

[jokos]

She needs to have multiple entry visa if she wants to enter the US again.

What if she receives a single entry Visa? Is there anything we could do to go on the vacation anyway? I mean, it should be obvious that this trip is only a vacation within her temporary US visit, right?

[peace999]

She does not need a multiple entry visa to return from carribean, canada or mexico if the trip is less than 30 days.
She should hold on to her I-94 card ( the card given to her when entering US from norway) and she will be allowed to re enter US
from the carribean visit on showing that I-94 card.

I-94 is to deposited with the airlines when leaving US for home ( norway), so her correct departure is recorded.