All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
It is permissible to donate on behalf of the deceased parents, and there is no harm in this. The evidence on this is that it is confirmed that Sa'd Ibn 'Ubaadah inquired the Prophet as to whether or not he may donate on behalf of his deceased mother and he allowed him to so. [Al-Bukhari] It is also reported that a man asked: "O Prophet of Allaah () my mother died suddenly and if she were to speak, she would have asked me to donate on her behalf, is it permissible for me to donate on her behalf?" The Prophet replied: "Yes." [Al-Bukhari and Muslim]
Allaah Knows best.