Overbearing MIL

Ok does anyone else have a MIL or anyone else who is completely overbearing?! My MIL just stopped by and started telling us how she is going to buy a new car a stoller and car seat for when she takes the baby. She lives 45 mins away, smokes in her cars...there is no way she is taking my baby anywhere! To top it off she keeps Thanking me, for having the baby! I think she thinks I am her surrogate and that this baby is hers!! I love her, and I know she means well and that my hormones are a little off balance... But how do you nicely tell someone to back the F off!! I already mentioned that the baby won't be leaving my side for a very long time and to calm down, and that she shouldn't expect to take the baby anywhere... Her answer to that was "oh I'll give you a week with the baby!" Jokingly, but really?!