Thank you all for the feedback, it was very helpful 
I decided to push both A and B further to try to clarify the story in both, and did some more research and thumbnails. I need some storytelling (and interior scene) practice, so maybe Iโll finish both if they turn out good 
Any thoughts about the storytelling in these images now? 

A - Itโs bad luck to open an umbrella inside
I decided to change the timing, and show this in action - as the girl is opening the umbrella. The mother is freaking out, trying to stop her, because she is superstitious and thinks it is bad luck. To show that she is superstitious I plan to include details that hint at this - good luck symbols all over the living room. Also the furniture is all very soft, round shapes, so that the umbrella really stands out as something dangerous.
I read somewhere that superstition is really just a way to try to control the uncontrollable (read: life). The idea here is that the mother is anxious that something bad will happen, so she tries to shield the kid - but the kid wants (and needs) to explore the world.
@Chip-Valecek - interesting idea about the colour treatment. Iโm not sure I want it to be completely greyscale though, but maybe some sort of a monochrome, desaturated color for the room, so the inside of the umbrella really stands out 
B - When 13 people eat at the same table, one will be dead within a year.
Thanks @KathrynAdebayo for your suggestions - I think Iโll make this into a tween birthday party instead 
The superstitious girl is now in the kitchen eating pizza from the box, which I think makes a lot more sense story wise. I made the empty chair more prominent, and will connect it visually to the girl by having the same color on her clothes and a jacket on the chair. Then Iโll include some more bad luck symbols as hints - a calender with nr. 13 on it, she is afraid of the black cat. Also changed the composition a bit to make it less static.