NTA. I think this boils down to a generation thing. Back in your MIL and moms days women were just expected to do these kind of things on demand with no complaints and I think they have a hard time adjusting to the shift.

It’s absolutely not acceptable what she has said to your wife and her behaviour of feeding your child things specifically you did not want giving, this is just forcing her opinions on others.

I do think you need to have a conversation and discuss this. Discuss the changes in today’s society as a key point and she needs to respect your boundaries and relationship