at home = at home (having arranged treatings - tea, food etc.)?

It is just a common phrase meaning the person saying the phrase knows for sure that the people will be at Mr and Mrs So's house along with the other people "so" At that time..."6:00 p.m."

Yes, it means that the person saying it knows that those people will be at that person's house at that time...

I have the vague recollection that "at home" at some time in the past may have meant the party would not only be physically at home, but "at home" in the sense of receiving visitors.

I've no idea where I got that impression, but I'm sure it is now obsolete.

Dang, we're over a year late.

In earlier times to announce that one was "at home" meant that you were receiving any of your friends and family who cared to attend. You would serve refreshments. One often had a regular day and time.

Thank you all.

I agree.

Yeah, I thought about the party thing...And I agree with you both as well...I just thought from the last sentence of Ori's post, that it came from a book....It sounded like it was a murder mystery or something where the person was saying that they knew these people would be home at that time...I think I was just too broad...

If we had known the time frame in the story, we might have done better.

I ran through a lot of these social traditions in Mark Twain's The Gilded Age. I have to say it was more informative than uplifting, and with little of his well known humor.

I like you Ori! I am going to add you as my friend!