A cab from SFO to the Hills will be more like $100 each way. Pre-booked car will be $150 round trip, plus tip. So a rental car is clearly cheaper than either of those.
There are no hotels in Los Altos Hills. In fact, there are no businesses at all in Los Altos Hills, that's the way they like it. Nearest economy/midrange hotels are along El Camino Real in either Palo Alto or Mountain View. Nearest luxury-type hotel would probably be the Rosewood at Sand Hill road and I280.