Selfish grandparents

So it’s my daughters first birthday party on Saturday invitations went out 2 months in advance. My parents and his parents just don’t get on. It’s mainly my husbands mother she’s just odd and takes offence to everything, so they have decided to book a holiday going on Saturday knowing it was our daughters party now is it me or should his parents be coming to their granddaughters 1st birthday party. My parents have said they want to put aside their differences and would welcome them with open arms but his mother is still being funny. Problem is this is causing an argument between me and my husband as I think it’s wrong and selfish of them not to come to the party and he thinks it’s fine and I’m over reacting