Cell phone
It's the end of the world but cell phones still work and never need to be charged.
shareI hope they still had internet as well.
My Chimp DNA seems to have lost its password temporarily. Sluggr-2
Totally logical. Also, when your daughter gets picked up and taken in the sky by a flying zombie, just text her! Then, when she receives it, she won't be in touch along the way or even reply to your message until getting there. Nothing to be worried about, which is why we can see the family stopping along the way to sing songs around a campfire.
Yep, all plausible.