Definitely not Yucca whipplei (common name: our lord's candle). Yucca's have very stiff leaves (the kind that will impale you if you land on them). The nolina has thin leaves that are "easily" brushed aside and flexible. Based on the photo, this is a species of nolina.
One of my Cali ecology books refers to this as Wolf's Bear Grass or Wolf's Nolina. The book goes on to say that its commonly mistaken for Parry's Nolina, which is actually a smaller variation that occurs on the slopes of Jacinto and the Santa Rosas