Ask Mr. Smarty Plants

You don't mention erosion control, but I wouldn't be surprised if that is one concern for your steep slope.  Las Pilitas Nursery in Escondido and Santa Margarita specializes in plants native to California and they have an excellent web page with recommendations for native plants for many situations.  You might like to read one in particular, Simple erosion control for a hillside or garden slope, with lists of suggested plants for slopes at the very end of the article.  Unfortunately for you, I think most of their suggestions have blossoms that will attract bees.  Flowering plants need pollinators and many pollinators turn out to be bees of some sort. Bees are not normally agressive unless you disturb their hive.  However, if you are especially allergic to bee stings, I can understand your concern.  You can see a list of plants and the pollinators that they attract in Selecting Plants for Pollinators: A Regional Guide for Farmers, Land Managers, and Gardeners in the California Coastal Chaparral Forest and Shrub Province.  Here are the two plants that appear on both lists and don't have bees listed as pollinators—Arctostaphylos uva-ursi (kinnikinnick) and Eriogonum fasciculatum (Eastern Mojave buckwheat).  The "Selecting Plants..." article says that the pollinators are butterflies and moths for the buckwheat, but our Native Plant Database says it's a favorite of bees and butterflies—so you may be taking your chances with it.

Aesculus californica (California buckeye) occurs on the "Selecting Plants..." list without bee pollinators but it's not on the Las Pilitas list. It should work well, however.  Las Pilitas says that it is toxic to non-native bees, but native bees appear to like it—so, again, you may be taking your chances with it.

Juniperus communis (common juniper) on the Las Pilitas list would not attract bees and neither of the two small oaks on their list, Quercus dumosa (coastal sage scrub oak) and Quercus durata, would attract bees.

You can look through our California-Southern Recommended list for other likely candidates.  You can use the NARROW YOUR SEARCH option to choose criteria important to you.  For instance, you could choose 'Shrub' or "Grass/grass-like" from the GENERAL APPEARANCE category to narrow the list.  Grasses, in general, are wind pollinated and would not attract bees. Here are some attractive California grasses from the list:

Achnatherum hymenoides (Indian ricegrass)

Festuca californica (California fescue)

Koeleria macrantha (prairie Junegrass)

Melica imperfecta (smallflower melicgrass)