Sounds like an old lady that is alone and her mind is not what it once was. Got to go slow with them. They let their worries get the best of them. All you can do is repeat that you don't know how long it will take to get the truck fixed but soon as it's repaired she's first in line. Repeat over as needed.
As to gets dark by 7. Don't worry I'll be there first thing tomorrow to finish, again repeat as needed to reassure.