I think that there are a couple of assumptions that are presented in the question that might need to be fleshed out a bit. The first would be that Laura does not question the Status Quo. I am not entirely certain that Laura becomes an apologist for the Status Quo at the end of the story. Mansfield's gift is to make the ending so complex and intricate that there is only room for debate and discussion. Yet, I don't see Laura as someone who "does not question" the Status Quo. I think that she is one who has experienced something profound with seeing death, contrasting it with life, and seeking to understand her own conception of self within such a dynamic. Yet, I don't see her as someone who has abandoned her sense of rebellion or questioning. Rather, I think that she is working towards formulating some level of articulation regarding the profound nature of being in the world and how this connects all human beings.
I think that the second premise that might have to be debated is the role and function of Laura's mother. Laura's mother might have a role in seeing her daughters plan the garden party, but it seems to me that this is it in terms of what she desires. Laura's mother is not one concerned with the idea of seeing her daughter's emotional transformation as being the center of her being. She is more concerned with the idea of the garden party and how it will come about through her daughters. I think that her suggestion to take flowers to the dead man's widow is a gesture to Laura in order to move her from cancelling the garden party. Yet, I don't see her character as existing in anything more than the party's realization.