The HHV is not particularly close to a large Supermarket. The best bet for a sort of mini Supermarket is the Foodland in the Ala Moana Center.
http://www.alamoanacenter.com/foodland_supermarket.htm
A rather long walk, but doable. TheBus will take you there from the stop across the street. It will drop you off in the front, but most of the returns are from the rear. Ask for a transfer which can be used for your return trip.
http://www.flyertalk.com/forum/hawaii/883338-bus.html
A smaller mini Supermarket on Waikiki is Food Pantry. It is also a long walk from HHV.
htttp://www.yelp.com/biz/food-pantry-ltd-honolulu-2
PS When will you be there?