Need Advice for a Sympathy Card/gift

Did they live with the dad? How old is the boy? I would check the paper for the obit and see if there are any funds (maybe a college fund) that are being set up or at least to get more information. If nothing else you can send a sympathy card to the funeral home. It would probably be impersonal to send a gift card or cash if you're not familiar with who the child will have to live with, but at least a card or money towards college would be appropriate.

Are you able to pay them a visit and offer your condolences, then hand them the card at that time.

Have your daughter make a dish and take it over to the house and extend her condolences on behalf of your family, and ask if there is anything she can do.

Blessings...