Actually I do pretty much treat her like my own mother. I’m very diligent at making sure both grandmothers have equal time with their grandkids. I get her something from me on Mother’s Day and her birthday.
Then I repeat: you have a husband problem, not a mother in law problem. If, as you say, you are as kind and attentive with her as you are with your own mother, then you're left with 2 options. 1, Request your husband to tackle her about both her overstepping of boundaries and her lack of gifts and cards on special occasions. Or, alternatively, just stop buying her cards and gifts for any occasions and leave it to your husband to sort out. You've received several excellent suggestions Lilac, none of which, thus far, having met your approval. If all else fails, you'll probably need to just cut off all contact with her and leave her with entirely to your husband to deal with. Do let us know how you get on won't you.