No resturants were open at that hour.
If the pizza was frozen, there would have been no time left to eat it, as the party-goers left the van Dam home within 30 minutes.
Where was the Daddy, whilst Mom was out dancing the night away?
Was he asleep, or in some way incapacitated, and unable to hear some one in the house?
It smells.
Perhaps if her pickup for the night was a sixteen year old but that's unlikely.