The Light Rail line is around a 20 minute walk from the Cruise Terminal so I wouldn't recommend it, especially not with children or luggage.
Personally, I would get a Taxi since it's a 8-10 minute drive from the terminal. Try to disembark as close to 9am as possible, as there is always heavy traffic until around 9:15am in that area. You will be directed by staff to where taxis will be waiting for pick up, you won't have to call them.