You can get her a 100th satin sash and a tiara. Maybe a bouquet, like “Queen for the Day.” Also, call the facility where she is, and ask for suggestions. Local newspapers sometimes will come and take a photo. Not many make it to 100, it should be a big deal.
Thaat’s on my list for today — call the assisted living home. I’ve tried once, and they weren’t answering their pones yet. (2 hours time difference) It’s time to try again.