What is Daisy's real response to the part, according to Nick?

What "part" are you referring to?

I meant party

This comes before Nick tells Gatsby "Of course she did," when Gatsby said about Daisy, "She didn't like it."

".......the rest offended her — and inarguably, because it wasn’t a gesture but an emotion. She was appalled by West Egg, this unprecedented “place” that Broadway had begotten upon a Long Island fishing village — appalled by its raw vigor that chafed under the old euphemisms and by the too obtrusive fate that herded its inhabitants along a short-cut from nothing to nothing. She saw something awful in the very simplicity she failed to understand."