Afoot & Afield: San Diego County: 282 Spectacular Outings Along the Coast, Foothills, Mountains, and Desert

Get her the latest editions of 50 Best Hikes in San Diego and/or Afoot and Afield in San Diego. Wrap the books up with a gift certificate to a local coffee shop in her neighborhood (ask for recommendations on r/FoodSanDiego -- the regulars over there know their stuff.)