It's tricky, because it probably goes directly to her core values. If she is being valued and given credibility on the back to what she does for her husband, and son, it would appear to her that you not doing it is challenging what she sees as her own value, maybe?
She might also see double value in how she is able to advise you, about those roles. Her utility goes up a little.
But you're doing her out of a job!
It's quite complicated, because people's self-worth is at stake. And something has to give.
Would it be possible to sit her down and have an honest, open conversation with her about why it is different for you than it was for her? And comprehensively explain it? And yes, a bit of positive feedback for her to have raised a son who understands.
It's really asking for her to do a crash course in feminism, isn't it.
For what it's worth, it's an incredibly common issue.
My own mil used to complain if, when they came round, DH made them coffee and not me.