Toddler going away for first time?

My son is almost two, and a family reunion is happening next weekend. I am in college right now, so I cannot leave until friday. His grandma watches him while I'm gone on the paternal side. Her daughter wants to leave tomorrow and that means they would have to take my son with them. I don't have any trust issues, but I'm just pissed because I have asked this girl if she could go on Wednesday but she will not budge. She isn't the empathetic type. I have never been away this long from him before and was wondering how other people have coped with it. Thank you!