If she went to an early evening movie she could have turned her phone off while in the theater around 6 PM. Is her mom's comment about texting in all caps being taken out of context or was her mom concerned and texting in all caps on Tuesday when she didn't hear from Zuzu for an hour?
Rangra showings are typically 6:30 & 9:30, so that would make sense if they did go to a movie before having dinner at RF's place. It's not the type of theater to police cell phones, though.