Jersey Shore Martini
Assuming that your wife and company are looking for the modern incarnation of the martini. i.e., vodka-based, sweet, flavored, etc. The Mill in Spring Lake Heights does a $5 martini happy hour with half-priced apps. It's a nice space with a good view.
If, however, I am wrong and the ladies are looking for a decent "true" martini, they have to travel. The Watermark and Langosta Lounge in Asbury Park have a couple of premium gins to select from, better than most places. Neither uses good vermouth. Trinity in Keyport has the best gin selection I know of, Noilly vermouth, I believe, and at least one kind of bitters. Best "martini" spot in Monmouth county.
Surprisingly, the best martinis I have had of late have come from chain restaurants: Bonefish Grill (Brick), Cheescake Factory (Freehold) with an honorable mention going to Tiffany's (Toms River). All have an extensive martini selection which I'm sure will be a hit with your wife and her girlfriends. Good Luck.