Mom mad we didn't stay

Sh

I just would love some input on this..my daughter is 9 months old, she has her bath at 630 and is in bed by 7. tonight my mom invited us over for dinner because my brother is visiting. I say of course but only if dinner is ready by 6 because we have baby on schedule, she agreed. So we get there, she hasn't even started cooking at 6pm. by 7pm she said another 30 min and I told her we really have to head out because baby is already over tired and is usually asleep by now. she got mad, gave me the silent treatment, and my brother was wondering why we couldn't stay another 15min since we were already so late (he doesn't have kids). So I basically felt like a total bitch..got baby home for her bath, she was screaming rubbing her eyes, sooo tired. I feel guilty and horrible for forcing her to stay up, and I also feel guilty for leaving when my mom had cooked us a meal. what would u feel? what would u say to my Mom?? here's my girl just because :)