@Whatisgoingonhere
Her husband was inside that woman for 9 month. Then he grew up in her house. They share the mitochondrial DNA of their long distant ancestors. All of this makes the mother in law a close relation. The husband is pissed off by all this which suggests he would like to maintain a relationship with his mother.
Excluding a close member of your family from a funeral is so rude you cannot expect to come out of it unscathed.
Funerals are traditionally public events in England anyway, so excluding a close family member from a public event is doubly rude.
If my husband pulled that stunt on my mother, because MIL doesn't buy enough Christmas presents, which is the reason that has been given, I would be incandescent.
The level of insult to the mother is huge. It's also a massive insult to the husband, who has no good way out of this.
Funerals are not, traditionally, about guarding and policing who is allowed to have feelings about the death. They are not a place where you say 'My sorrow is the most important and nobody else's feelings matter' - which is what is in fact happening here. Her mother in law isn't allowed to have any feelings because she doesn't buy Christmas presents. And her husband's feelings don't matter at all and therefore he is 'sulking', like a child, rather than genuinely aggrieved with a good reason to be pissed off.
As John Donne says, No man is an island entire of itself, Every man is a piece of the continent, A part of the main. Any man's death diminishes me because I am a piece of mankind, and therefore send not for whom the bell tolls, it tolls for thee.
That is the sentiment that has traditionally guided funerals, and why the whole community attends: that we are all part of a whole, we come together as humans to recognise the life of a fellow human, together and everybody in a community has the right to have feelings, to mourn and to pay their respects. Feelings are not ring fenced to the In crowd.
It may be very 17th century of me, but I think it's a good sentiment and maybe a better foundation for mourning the passing of a parent than 'you don't buy me enough presents to come to my party'.