I am assuming that a “Hens Night Party” is the equivalent to what we call a “Bachelorette Party” If this is the case, then I would recommend getting a little something fun for the evening – maybe if you are going out for martinis, then get her a martini glass or something that says “Bride” on it. ALSO – definitely offer to buy her at least one of her drinks. I think that’s just proper etiquette. Let me know how it goes, babe!! HAVE HEAPS OF FUN.