100 Candles (2019)

Bernice, a 99 year old Queen Elizabeth fanatic, is about to receive her long-awaited letter from Lizzie, but she dies on the eve of her 100th birthday. Her loving grandson goes out of his way to get her that letter, bribing his awful wife to co-operate and pushing through with her 100th birthday party, despite the guest of honour being dead. He thinks he's pulling it off when unexpected guests join in the shenanigans and suspicion arises. But he's not willing to give up - not without that letter.