Fidyah

Q: Can you please advise me on the following:

My father had passed away and had made a Wassiyat in his will that we the heirs should discharge 1/3 of the Estate towards settling his religious liabilities.

Question: Must this money only go to the poor; or can we give it to students studying at a Maktab (who qualify as Zakaat recipients); or towards a Masjid for renovations and maintenance; or towards any Islamic relief effort; or where / what must this type of funds (Wassiyat) be used for?