Did she say why she doesn't want you there? There is a reason, but until you know what it is you won't know how to handle things. If she won't tell you then simply tell her you'll be there, because that's what parents do when their kid has a ceremony.
If she does give you a reason, be prepared to handle it calmly.
It may simply be she has a mistaken idea that no one's parents are coming and it isn't 'cool'. You can point out that there were x-number parents last time, or that you know Friend's-mom will be there too.
It might be that you cheer and take photos, which she now finds embarrassing, and you can promise to sit quietly and skip the pictures.
Perhaps she didn't submit a book this year and doesn't want you to know that she isn't getting an award.
So many possibilities, which is why you need to hear it from the source.