I have to admit it’s been a thorn over the years in this house too, I lost my mother when my eldest was 2, after that my mil assumed she would spend the day with us, me waiting on her had and foot as normal. I had 3 close together and worked full time and resented that she came first. My DH just couldn’t say no to her, and I would perhaps get some flowers, but no help entertaining the in-laws for the weekend.
Now they have all passed and the children are grown it’s different, I always get flowers/chocolates, it means more now, they do it themselves, not because dad told them to.
That said, if it’s just an ordinary day, couldn’t you arrange to go out with some girl friends, or visit your mum. A day for you without the children, not the spirit of Mother’s Day I know, but I think you deserve something.