Shirley - momzilla over there is going to have a rude awakening once that baby is in her arms. When she realizes that this baby, this tremendous responsibility, is HERS. And really, hers alone, as her husband will be working and the rest of you have your own lives.
I remember after I birthed my first, it was the middle of night, they brought my baby to me to nurse, and she just cried and cried. And nobody was there to help. I cried too, because I realized that this big job was completely mine. Of course, I recovered and we all lived (she's 5 now), but that was really hard. The first baby is like an "event" but then you realize it's just the beginning of a lot of hard work and maybe not a lot of help. I imagine that's only going to be worse for a new mom who has obviously overthought it.
So, maybe if you can swing it after a few days, go see her and new babe and see how they are. Shock may humble her. And, if you can, bring a dinner...it is so hard to cook one-handed while holding a baby.