My dads first birthday without him

So I lost my dad in Oct 2021 really suddenly and it’s still very much of a blur. His birthday is next week so it’s the first we will have without him. I really want to be there for my mum but I just don’t know what to do. I’ve thought about planning a day out with her and my son to take our minds off things, sending flowers, doing nothing. I just don’t know what is best.