For most people, a dust storm would be a pretty scary experience, to say the least. But what's striking about the reaction of Billie-Jo's family is how relatively matter-of-fact it all is. Instead of panicking and running around like headless chickens, they remain calm, focusing on the things that they need to do in such situations.
As the Kelbys have a lot of experience dealing with dust storms, they know the precise drill they must follow when one hits. And so, as soon as a storm descends upon the Kelbys' place, Ma immediately tells Billie-Jo to cover the beds, push the scatter rugs against the doors, and dampen the rags around the windows.
Ma appears to be calm and in control during what is obviously a very difficult experience for everyone. Once the storm has subsided, she wipes the dust off everything, prepares some coffee and biscuits, and patiently waits for her husband to come back home.
Even though Ma acted calmly and decisively during the dust storm, it still took quite a lot out of her. She rubs her lower back, which is an indication of pain, and sinks down into a chair at the kitchen table, which would suggest that she's incredibly tired.