Do the grandchildren of Salima have the right to claim their share of their grandfather M'hammed's land, knowing that the land is registered in the name of Salima's nephews, and there are indications that she verbally relinquished her share?

The ruling on this matter cannot be definitively determined because it falls under the category of disputes, which are the purview of the Sharia (definition) courts. It is important to note that depriving females of their share of inheritance—especially land or real estate—is an injustice and an transgression of God's limits. If a female relinquishes her right to the inheritance in favor of her male siblings due to this injustice and her lack of consent, then such a relinquishment is not valid, and her right must be restored to her.