Her comments can only bother you if you let them. As others have suggested, just let them wash over you, with a vague remark and a smile. She probably means well, and doesn’t have much going on in her own life, at present. Hopefully, when (if) life gets back to normal she will have other things to think about. Certainly don’t fall out with her about it, and when DH pipes up ask him if it’s him, or his mother talking.
Sadly, I nursed my MIL through cancer, while expecting her first GC. She never lived to see him. MILs can be a mixed blessing, but I never had much chance to learn how we would have got along. Well, I think.
My DD is a little like your MIL. She’s adopted, and we have very different ideas on how to do things. Her, “Why don’t you.......?” comments are met with, “Mmmmmm! That’s an idea!”