Regarding brand: If your sister doesn't have much of a preference for how the car drives*, or too concerned about luxury (comfort, features)**, it's hard to look at anything but a Honda or Toyota, or possibly a Saturn.
Regarding bodystyle: You mention hatch/wagon, however if your sister doesn't have much of a preference for how the car drives*, it's worth taking a look at small SUVs/crossovers as well. They aren't much less fuel-efficient, and will have more room and a better driving position for general around-town activities.
So, down to specific cars:
- Corolla Wagon: Great all-rounder, but they stopped selling those in '96, if I recall correctly. If you can find one with low miles and in good condition, that can be a good bet.
- Saturn SW2/LW300 wagons: Really underrated cars. The SW2 is more of a bare-bones transport car, but you get Honda reliability at a fraction price. The LW300 the higher-line version, overall a bit finer around the edges, and also a great car. Both are somewhat rare though.
- Honda CR-V: A great car, but the problem is that everyone and their mother wants one of these. Used car prices are incredibly high. I'm almost certain you couldn't find one with your specified criteria. Due to the newfound popularity for crossovers, CRVs and similar are very expensive compared to wagon/hatchback alternatives.
I'm mildly assuming that your sister isn't interested too much in how the car drives*. This is mostly because people who do care about how a car drives* are generally enthusiasts who have more knowledge to come to car-buying conclusions themselves. If this isn't the case, I'd be glad to revise my recommendations. Same goes for if she prefers something more luxurious.
*Speed, handling, fun-ness, etc.
** Comfort, features, etc.