Ok Matt, we'll do all the leg work for you.
The following manual tranny SUVs will get at least 3+ city and 3+ hwy over the Liberty:
Toyota RAV4 (2005 or earlier)
Honda CR-V (2006 or earlier)
Ford Escape/Mazda Tribute 4 cyl
Ford Escape/Mercury Mariner Hybrid (Auto only)
Jeep Liberty DIESEL (Auto only)
The Escape/Mariner Hybrids are pricey, but are significantly more fuel efficient. Especially if your mom does mostly city driving (28!!!)
Good luck!