What is the expiation for screaming and wailing over the deceased as a courtesy to their family, given that the one who did it has passed away and was ignorant of the prohibition thereof, and does giving charity on her behalf by her children expiate for her?

The expiation for wailing and screaming over the dead is through repentance, which involves regretting the act, refraining from it, and resolving not to return to it. As for one who dies before repenting, their matter is with Allah. It is permissible to seek forgiveness for them and to give charity on their behalf. Wailing, raising one's voice in lamentation, striking the cheeks, and tearing garments are forbidden.