Maybe someone can help me

I thought this was the movie, but it isn't. There was a movie that I saw when I was a little kid. It was in black and white (it's gotta be from the 40's or so) and in it there's a nucleur explosion or some kind of apocolyptic event and only like 3 or five people survive. They end up at this house and every now and again they venture out to see if there are nay other people that made it. And the only other thing I remember is that a girl (maybe a guy, but I'm sure it was a girl) ventures out one day, and now I could be mixing up movies because I was very young when I saw this and really really can't remember, but I thnik she runs into a monster that reminds me of the creature from the black lagoon. Does anyone know what movie that is? Or maybe it's a twilight zone episode? If anyone knows of anything that sounds vaguely familiar to this please post back. I really wish IMDB would put a movies like this section on each movie page. It would make things a lot easier.

Vic: Actually we met @ a fairy gathering
Emmett: What the Tony Awards?