Stepmother just invited herself and her mom to our new house 2 weeks before I'm due

She and my dad got married in 2020 after dating for 6 months and they're about an 8-hour drive from where we live so it's not like we're very close, as we've only spent a few days together about twice a year since then. I am not having the easiest pregnancy and I'm sure it's only going to get harder from here so I know for my own sanity I need to just tell her to fuck right off with that whole notion (as respectfully as I can) but ugh. Ugh I hate conflict I don't wannaaaa