Why would you even want to be friends with people that freakin rude? Give it a little more time, you will find both parents and kids that get along with you and yourr dd!!
I say screw 'um!
That one mom though, yeah, wouldn't even bother trying. Technically she gets points for honesty, but she'd get just as many if she'd been more polite and said "I'm sorry, I'm just nervous about your neighborhood. I'm sure it's just fine, but I'm going to have to cancel. Again, I'm really sorry for having this attitude and I know it's entirely my fault. I hope you don't hold it against me too much and will still come to playdates at my house?"