My parents are divorced. At whose house should the proposal delegation come?

The one who formally receives the proposal is your wali, that is, your father, even if you live with your mother. That does not mean your mother is set aside. Her agreement and blessing are very important, and she should be present or at least told in advance. Discuss it with each of them separately first. If their relationship is tense, the event can be held at your mother's house with your father present as wali, or at a neutral place. Avoid letting the occasion become an arena for old disputes. Allah says: “…And fear Allah, through whom you ask one another, and (respect) the ties of kinship” (Surah an-Nisa' 4:1). See The marriage wali.