Wedding gift ideas-PLEASE!!?

My cousin is sick and is getting married in one week so that her children will be cared for by the man she has been with for the past 8 years just in case she does p away. She's having a bone marrow transplant. The wedding has been put together very fast. Does anyone have any ideas as to what kind of gift I can buy for them or anything really nice I can do for them that is also budget friendly?? Thanks!!!