Giving charity on behalf of the deceased and whether the deceased will be aware of that

What is indicated by the Islamic texts is that the deceased
benefits from charity given by the living on his behalf, and his prayers for
him. Offering a sacrifice on his behalf is a kind of charity, so if the
giver is sincere in giving charity on behalf of the deceased and in praying
for him, then the deceased will benefit from that, and the one who prays for
him or gives charity on his behalf will be rewarded, by the grace and mercy
of Allaah. It is sufficient for him that Allaah knows of his sincerity and
good deed, and He will reward both parties. But as for the deceased being
aware of the identity of the one who is doing him this favour, there is no
shar’i evidence concerning that as far as we know. It is a matter of the
unseen, and cannot be known except through revelation from Allaah to His
Messenger (blessings and peace of Allaah be upon him). 

And Allaah is the source of strength. May Allaah sent
blessings upon our Prophet Muhammad and his family and Companions. End
quote 

Standing Committee For Academic Research and Issuing Fatwas