Is the prescribed punishment (hadd) to be carried out against one who violates the honor and dignity of the mother with immoral insults and curses? What are the conditions for that? And is his act considered slandering chaste women?

If the insults include an accusation of indecency (zina) or a denial of parentage, then it is slander (qadhf), which is forbidden and punishable by eighty lashes. However, if it does not include slander, the wronged person can complain to the Sharia courts, which will rule with whatever disciplinary action or admonishment they deem appropriate.