i was left money in a will...

My grand mom died august 29th 2014 I was told by family members that she left me money in her will...I am to receive this money if they don't find my long lost uncle. My mom is the executer on the will and she first told me I would have the money if they don't find him....my uncle told me that it stated in the will that if he isn't found august 29th 2015 the money belongs to me...but my mom and aunts insist on waiting another year to see if they can find him...can they do this if it was written that I should receive the money if he hasn't been found by the deadline?

Two questions:
1) Have you seen the will?
2) Are you or the estate in Ireland?

No I haven't seen the will but I was told that it said my name and that I should receive the money if he doesn't come forward and I am in USA ...P.a

This is an Irish forum. If the will is for an Irish estate then responses to queries here will be useful but if it is for a US estate it will be unlikely that anyone could answer you definitively.
In general though, you only know the contents of the will by report - and by your first post, the two reports differ.