Aibu about taking home leftovers?

[WhyamIBoredathome]

Ok, so as not to influence I won't say who I am.
Family member A invites member B and their family over for lunch.
Both families are made up of two adults and two children.
Person A does all the shopping and cooking for main course and nibbles.
Person B offers to bring dessert and spends time and effort making a Nigella cake recipe to bring.
Both families have a nice time and enjoy all the food. About a quarter of the cake is leftover.
On leaving Person B picks up the leftover cake to take it home. Person A's husband expresses surprise that they aren't leaving it behind. Person B takes cake as they cooked it so felt this is fair.

Who is being unreasonable?

Is person B right to take cake as they put time and effort into baking?
Or is person A right expecting cake to be left as they bought and cooked main course (everything got eaten) and hosted.

Is she on a budget? Maybe she’s harder up than she might let on. And thinks, as you’re family, it’s ok to be more relaxed about social etiquette than she might be elsewhere...

Ask her to bring the starter next time.

Person b is very rude. It us a gift for the hat, you leave it for them to enjoy.

Host doh, not hat😂😂😂

Oh Gawd, I couldn't care less if anyone took the leftovers home with them. Why on earth would anyone mind? I know if I hosted and they wanted to take the leftovers home I really couldn't get worked up about it!
Same if it was a bottle of wine or whatever.

I often take some cake home if I brought it, but only after leaving most of it. It's more about wanting the plate back than wanting the cake. It depends on how often I see the person.

There's no way I'd just pick up the cake and take it all home.

I'm person A for those who missed that.
Cake was in foil, no plate, so ni excuse there.
Defo not short of cash, in fact has far more money than me.
It has never bothered me that much, the reason I put an aibu was because my OH commented about it and said after they'd left how rude she was.

I don't like it when people leave us cake, as we don't really eat it and it ends up cluttering our freezer or being given to the hens, which seems a waste, so I would prefer it if people took it away, but if the host likes cake and would want to keep it it is a bit odd.

Next time get OH to say "Oh, I see. I fancied it for my tea, actually - could you leave us half?" and see what happens?

I absolutely think it was wrong of sil to just take away the leftovers but... by way of a hijack, suppose you were going to parents house for Christmas and taking all the food to feed 15 for Christmas day and boxing day and cooking it whilst there, ( but absolutely not washing up) what is the etiquette on removal of leftovers?

Maybe she assumed you’d chuck it away (which is what I’d probably do after a dinner party) and so thought she’d take it instead?

Chuck away home made cake?

Why would you chuck away a perfectly good cake brandbrandbrandy?

Person B is in the wrong.

Chuck away cake?
Anyway, if she thought that, she should have had the manners to ask if OP wanted it.

Waste, especially food waste is my pet hate.

Why on earth would you throw it out?