What is the expiation for having dealt with magic and placed it in front of houses ten years ago?

Your relative must offer sincere repentance to Allah, and that is her expiation. If her sorcery caused injustice to others, she must seek their forgiveness, unless doing so would lead to greater harm. She must also retrieve and nullify the magic she placed in front of one of the houses, if she is able. Otherwise, she is only required to repent to Allah.