What's the Name of That Book??? discussion

At the beginning, a little girl is saved from a nuclear attack by having gone down to the cellar of gas station /convenience store.
In the cellar with her is the owner/old man. They are trapped there, both because the cellar has caved in/is buried and the fear of radiation outside.
They are there for months & have food/water. He is dying and gets the little girl to dig out before he dies.
Other: the planet is going thru a nuclear winter and the sun is obscured for years... until the end of the book.
Lots of traveling.
The main character is a woman.. 20s?30s? Roving gangs bring destruction.

When did you read it?

Was it for kids, teens, or adults?

Adults, definitely. Maybe YA? Read within the last few years

Possibly Swan Song by Robert Mc Cammon?

Yes!! Thank you