San Francisco is a great place to visit and some accessible hiking. The area around Ocean Beach leads to Lands End and the Sutro Heights. They can also walk over the Golden Gate Bridge or take a bus and go to the Marin Headlands where there is great hiking. I remember many years about taking a bus to Stinson Beach and Mount Tam. They can also take BART to Redwood Regional Park in the East Bay. Beyond hikes and walks, it is a great area to visit. As others have said, however, November can be beautiful or rainy. Yosemite may be tough in such a short trip as it is fairly far away, but there are likely buses that go there.