Well, the mayor isnt normal herself, granny made that suplex with all intentions of opening her skull.
Maybe her reason to hate her is understandable, but unless she Ramia is the literal reason for the world end i think 30 years is a little much to hold a grudge, more so when other involved parties seem less prone to that grudge.
@TGS I checked your pixiv and saw a picture side by side of a younger Ramia and her present self, really cool art, it drives home the things she had to deal with even more when you see how she was before the scars. A question, if it isnt too spoilery for you to answer, is does Ramia know/use magic or she is the full-brawn type?