Two issues here.
One; the son's behaviour in cancelling so late and swearing at his father.
Two; Daughter in law held responsible
Issue no. one; rude to leave it so late to cancel, no chance of a refund, and two very feeble excuses. Plenty of time to book a dog sitter, and unlikely that school would be organise events so soon after start of school term.
Issue no Two: it is all the daughter -in-law's fault.
It may be so, but we do not know all sides of the situation.
I had a friend whose husband at the very last minute, would refuse to go to her large family occasions. (weddings, funerals, christenings, anniversaries) things booked for a long time involving expense; she was not a confident driver so generally had to make excuses and stay away.
I wonder if this couple is as financially secure as they appear? He may appear to be comfortably well off , but equally they are spending freely with expensive tastes and may be living above their means. (echoes of a recent post where the couple were borrowing more and more money from parents for essentials while spending on expensive holidays and house improvements.)
The fact that the son is avoiding contact with his brothers could suggest deeper problems , not necessarily wife related.
Equally, it could be that neither enjoy family get-togethers and find them overwhelming.
I have a very small family so have little experience of these events but know from friends some dread extended family celebrations whilst others take deep offence if all family members do not attend.
All I can suggest is, say nothing, wait to see if son offers to pay for the accommodation, and the OP receives some acknowledgement of her birthday.