Just wanted to underline the difference between asking and pressuring. My take is that Sinis could always be OK with the mother asking his wife, an adult, to the memorial or anywhaere else. He would also be right and justified in preventing his mother from pressuring for it. It is entirely reasonable for any head of household, man or woman, to forbid hard sell tactics and guilt trips in their own home.
And if a simple "no" isn't enough, Blacksheep's questioning approach works well; I've tried it!