Whose house rules for eating should apply?

I had my son, his wife and their two young daughters, 2 and 4, over for dinner. We have never had an “official dinner” before this at my house.
I was kind of excited about a special dessert I’d put together, especially for the oldest girl. It was lemon pudding cake upon which I would pour real strawberry juice (the oldest loves strawberries) and I was going to put banana slices on it (they are both banana monsters!)
The girls had a hand in making the dessert. We had fun throwing trimmed strawberries, some with a bite taken out of it, some whole, into the blender, and the youngest’s eyes got really big when I turned it on and it liquefied them. They both had a small cupful to drink too.

So, a few hours later it was time to eat. I was dishing up their food. I put a little baked beans on the oldest’s plate, and a bit of tomato and a few bites of hamburger from the grill. She said she didn’t want them and I said, what I’ve always said to my kids, “Then don’t eat ‘em!”
I also put a half ear of corn on the cob, a whole cooked hot dog, and I put 2 potato chips on her plate.
She ate all the hot dog and both chips. Then she chowed down on the corn.
So I gave her another half ear of corn and she worked her way around that one.
I said, “Are ya done?”
She said, “Yes! Can I have cake now?” She was excited.
Before I could answer her mother jumps in with “You have to eat everything on your plate first!”
And the battle was on, with tempers and frustrations getting high on both sides.
I felt so bad. I mean, I know Mom does that, but if I’d known it was going to happen at my house, with my food, I would not have put any thing on her plate that she didn’t want.

So, she never did eat all of her food (pretty sure she was full anyway) and she got in trouble and was put in time out.

I quietly threw a tea towel over the cake to get it out of sight, and put it in a corner of the kitchen counter, hoping they’d just forget. Maybe they did. Nobody asked for any, anyway (and it was REALLY good, fyi.)

I was so frustrated and sad for my granddaughter.

I mean, now I know, and things will be handled differently next time, but what do you guys think?

Doesn’t the same thing apply to behavior? Shouldn’t the house rules apply? If the kids can jump on the couch at home but the host or hostess doesn’t want them jumping on the their furniture, does the host(ess) have the right to say something?