Dave... Lots of great advice and many thanks to all who posted.
The total site, Mom's and the developer's, is hard to describe in words. It encompasses several canyons, creeks, ridges, heavily wooded and in places very rugged with nice vistas... and poison oak!
If construction were to happen, the way Mom's home is situated, she could not see any of it and there would be no construction or new homeowner traffic on her culdesac. Her home is on the far upper edge of the project at an elevation of 525' and the proposed road starts at 450' (On Mom's land) and follows the canyon ridges down to 250' elevation.
I stopped by Mom's after work today and she said two of the developer's partners came by to "Introduce" themselves and leave her with a project map and map from the survey they had done on her property. (Yes, in CA, Surveyors don't need the property owner's permission to do their work... something dating back to the Gold Rush days as I understand...)
The maps look interesting, but as Mom told them, "They are only paper." She also told them if they were at all serious about her land, to put their proposal in writing and she would have "Her" people take a look... and she wished them well.