Family Class

public class Family : Element

public void GetInfoForSymbols(Family family)
{
    StringBuilder message = new StringBuilder("Selected element's family name is : " + family.Name);
    ISet<ElementId> familySymbolIds = family.GetFamilySymbolIds();

    if (familySymbolIds.Count == 0)
    {
        message.AppendLine("Contains no family symbols.");
    }
    else
    {
        message.AppendLine("The family symbols contained in this family are : ");

        // Get family symbols which is contained in this family
        foreach (ElementId id in familySymbolIds)
        {
            FamilySymbol familySymbol = family.Document.GetElement(id) as FamilySymbol;
            // Get family symbol name
            message.AppendLine("\nName: " + familySymbol.Name);
            foreach (ElementId materialId in familySymbol.GetMaterialIds(false))
            {
                Material material = familySymbol.Document.GetElement(materialId) as Material;
                message.AppendLine("\nMaterial : " + material.Name);
            }
        }
    }

    TaskDialog.Show("Revit",message.ToString());
}