In addition to charity being a source of help for our family, relatives, neighbors and other members of the society, it is also an Ibadah (with Zakat being an obligatory one). Considering it’s nature as an Ibadah, I see no harm if a person hopes that GOD will protect him and reward Him both in this world and in the world hereafter. While doing any Ibadah, we do feel these kind of emotions and sometimes even express them in words . Just like a person can pray (Salah) to Allah and ask for protection against any disease, similarly, he can also do some charity and ask for Allah’s protection because they’re both a form of Ibadah.