What to wear for mother/daughter ice skating day?

Just wear leggings that you might wear during the cooler months with a fleece jacket or a sweatshirt that you can slip on over your tshirt/shirt.  One thing: if/when you fall, try to land on your butt and don't use your arms to brace the fall (you'll hurt your wrists/hands).  Also- keep your knees bent when you're on the ice.  If I'm at a public session to work on my hockey skating, I see people that have their knees locked and inevitably they end up falling.

No, that's overboard, especially since you don't skate and the event is at an indoor arena.

Wear what you might wear to actively exercise in cool weather. If they offer knee, elbow, and wrist protection, take it.

From my understanding, people wear helmets now when they Ice skate. Maybe some elbow pads, careful trying to catch yourself with your hands if you are 30/35 plus. Broken wrist are quite common from catching oneself.  That outfit may work on a pond or lake outdoors.  Inside rink it's too much.

that's a little over the top. just some jeans, a turtleneck sweater and an insulated puffy vest ought to do it.