Carol... How lovely for your daughter to be wearing something from her great grandmother. I'm sorry she's having trouble at school. I hope it passes and that she can be comfortable wearing whatever she wants again! The charm of the wall sounds very interesting.
Here's a quick read from Wiipedia about the Hamsa: (I think it's interesting that its presence is in several religions)
The Hamsa (Arabic: خمسة, Khamsa‎, literally "five", Hebrew: חמסה, Khamsa‎) is a symbol used in amulets, charms and jewelry to protect against the "evil eye." [1]
An alternative Islamic name for this charm is the Hand of Fatima or Eye of Fatima, in reference to Fatima Zahra, the daughter of Muhammed. An alternative Jewish name is the Hand of Miriam, in reference to Miriam, the sister of Moses and Aaron. It is a kind of "protecting hand" or "hand of God".
Some associate the significance of the five fingers to the five books of the Torah for Jews, the Five Pillars of Islam for Sunnis, or the five People of the Cloak for Shi'ites. This symbolism may have evolved at a later stage, in view of the fact that archaeological evidence suggests the hamsa predates both religions.
In recent years some activists for Middle East peace have chosen to wear the hamsa as a symbol of the similarities of origins and tradition between the Islamic and Jewish faiths. The fingers can point up or down.
Hamsas are popular as charms and decorations in Israel and are not considered to have any Islamic connection other than the Arabic name. Among Jews, fish are considered to be a symbol of good luck, so many hamsas are also decorated with fish images. Hamsas are incorporated in wall plaques, mobiles, keychains and necklaces. Sometimes they are inscribed with Hebrew prayers, such as the Sh'ma, the Birkat HaBayit (Blessing for the Home), or the Tefilat HaDerech (Traveler's Prayer).