Unfortunately, no they can't. They are attached to a specific pass. However, I'm not really sure where you redeem the "Skip the Line" pass. Are the associates able to scan your pass at the ride? I've never seen that done before.
Depending on the fine print, as long as there are no restrictions to certain rides, your mother might be able to use it on the Antique Cars.
We have five season passes and four of us received the perks email yesterday. My minor child was the only one who did not. We got a 9.99 t-shirt deal, a $19.99 bring a friend, a move to the front of the line pass, and 15% off food.
Can the perks be used by a different person? My mother is in a wheelchair and cannot ride roller coasters so she won't be using her pass to skip the line! The email says it's on the season pass :/