If you need one day a year for your DH and DC to show you how much they love you and appreciate you, then you've got a dysfunctional family and need to address that.
If breakfast in bed is your thing, surely that can be accommodated more than once a year on a particular day.
If you want "a break from the cooking" then maybe you should be having a conversation with your family about sharing cooking, washing dishes and going out for lunch when you want to rather than on a particular day.
Your DM and MIL do not stop being mothers just because their children have left home; so stop being so precious with comments such as "I'm the one who does the mothering", "Mother's Day should be about those who are doing active mothering", "She's had her turn". Heard every flipping year on Mumsnet (though thankfully never in real life).
Get over yourselves 