This is a long shot but does anyone know if its possible to get a greeting card from the Pope in the way you get one from the Queen, on reaching 100th birthday?
Not as far as I am aware. Remember the Pope is head of the worldwide catholic church not just 1 country so there are a lot more people to cover.
If anyone would know it would be the Priest at your church, if such a thing is available I am sure that the recipient would need to be a devoted life long church attender as well as 100 years old. It would have to be recommended by the Priest.