You can say "the social worker called on the two sisters..." but it sounds a little archaic or old. I would usually prefer to say "the social worker visited the two sisters." Also, "the social worker called on the house of the two sisters" is not wrong in English. It just sounds too complicated.

"The social worker called on the two old sisters who were ill" Means like, s\he called for them, or 'went to them' whatever you mean by 'called on' (Called on can have two meaning. "Calling for" and "went to")

"Call on" because it means "to visit someone" -as in visit and have a conversation- meeting - etc. You can't meet and chat with the house.