Are the gold artifacts for which the wife's mother passed away considered an inheritance in which her sister inherits, or is it solely for her daughter? And if the sister does inherit from it, is it permissible to give its value in money?

The gold left by the wife's mother is an inheritance that is to be divided among the legal heirs. If the sister is an heir, she shares with the daughter in the inheritance according to her legal share. If the deceased left no one but her daughter and her full or paternal sister, then the daughter receives half of the gold as a prescribed share, and the sister receives the other half by ta'sib (residuary inheritance). The daughter does not have the right to compel her maternal aunt (the inheriting sister) to sell her share of the gold to her.