Bless you for caring, and acting on those feelings. And blessings for comfort & healing to the rest of you also walking through grief.
In lieu of the store-bought sympathy card (I especially detest those that rhyme!) a personal note detailing the reasons the departed made a positive impact on you will be much more meaningful. Sometimes you think "oh, I barely knew that person, it would be awkward to send the family a card" but really, it's the notes from unexpected sources that often mean the most. You expect to hear from family & close friends, but when you receive condolences from others more distant, and then to hear how their loved one touched their life, it means a lot.
In lieu of a meal just dropped off, a gift card to a restaurant, grocery store, or food/meal delivery service might be more useful. I agree, often you're overloaded with food right after the loss, much of it goes to waste, then weeks afterwards you wish it was back.
And maybe, instead of a stuffed toy (my kids never played with them) perhaps a gift card to a toy store, book store, or a place like the zoo or movie would be more welcome to the boy, and a nice diversion for the mom.
Since your husband is this boy's Cub Scout leader, perhaps he could find more practical ways this family will need help, and get the scouts involved. Maybe they already have a church or other organization that is helping them, and the scouts can tie in with them. This family may be needing help in the months to come, with chores the dad used to do, with leaf raking or snow shoveling or things like that.
Thanks for starting this thread, it's helping us all be more thoughtful.