Is it fair to say that the whole town is complicit in Homer's murder in "A Rose for Emily"?

The druggist should not have sold Emily the poison, just as a bartender should not sell more liquor to a drunk man who intends to drive home.  In doing that, the druggist does bear some responsibility. But responsibility differs from complicity, in that the latter involves “aiding and abetting” a criminal act with intentionality.  The fact is, the druggist was too weak to say no to the woman, which brings us to the issue of the culture of the town. Your question raises the issue of to what extent any community is responsible for the evil acts of its members. Certainly kindness, understanding, and compassion, as well as a good father and a society that did not disparage single women might have resulted in Emily not seeking out Homer, not needing him to the extent that she did, and the town not being afraid of confronting her when it needed to. Yet, in the long run Emily is responsible for her own actions:  she planned this murder very carefully, after all, and showed herself a rather strong although deeply wrong woman in doing so.