Just my 2 cents,
Inheritance doesnt need to be fair.
Even if the mother in law wants to give the house(bungalow) to charity nothing can be done.
The bungalow belong to her anyway.

The bungalow is not his nor his wife to begin with, he can be angry if the mother in law wanted the 500k house to be split between the brother and his wife.

Parents owes their children nothing, they have provided shelter, food and education to their children. Getting inheritance is an added bonus.

I think using children as a reason is quite selfish. having children is his wife and his decision and responsibility. if they want their children to have a better future then its their responsibility not their grandmothers.