I think it is reasonable for spouses to not engage in this kind of texting, although in most cases it probably would not “mean” anything besides basic human courtesy and friendliness. But your husband has to know that, and you haven’t mentioned anything about telling him that it bugs you. So that would be your first step.
While awkward, the woman might be attempting to be friendly with you, too. I know sometimes I can be prone to giving advice when people share problems, because I think that’s what they’re after, when really they just want to vent. “I’m so tired lately, Bobby’s having nightmares again and keeping us up all night.” “Oh, we tried warm milk before bed when Susie had that and it seemed to help her.” It doesn’t necessarily mean that she thinks you’re a bad mother or wife. If you don’t want the advice, give short, non-committal responses when she offers it, and if you have been confiding problems with her and that’s when the advice comes in, quit doing that. Complaining often creeps into conversation as a “filler,” so if that’s a habit you have I’d work on that to stop the unsolicited advice. If it continues, especially if it comes out of nowhere, you can be a bit firmer, “Thanks, but I think I’ll figure this out on my own.” And then make yourself scarce when she’s around.
I guess based on what you’ve written here, and the other issues you’ve written about in the past, I would lean towards giving others the benefit of the doubt at least for now, and working on how to communicate your wishes clearly and respectfully.