بسم الله الرحمن الرحيم
(Fatwa: 831/831/M=09/1437)
Yes, one may do sadaqah on behalf of the Holy Prophet Muhammad, may peace and blessings of Allah be upon him, and of his Companions, may Allah be pleased with them. And something may be given as gift on behalf of the Holy Prophet Muhammad, may peace and blessings of Allah be upon him. The rewards of all these deeds shall reach to the Holy Prophet Muhammad, may peace and blessings of Allah be upon him, and to his Companions, may Allah be pleased with them.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband