It sounds like you have a lot of pent up anger and even rage at your mother that is unrelated to this incident. You're angry she doesn't know who your father is, that she didn't chose a step-father who would be present in your life in the same way she is present in her step-daughter's life, that your grandparents are elderly, that she wasn't in your life in the way you wanted her to be, didn't treat you the way you wanted when you were growing up, etc.

Those are all legitimate things to be hurt by and should be addressed (either with her in an appropriate way if she has the capacity to address them with you) or in therapy or both. BUT those are all things that are at least somewhat removed from the fact that she has a relationship with her step-daughter and is excited for her future grandchild. Being angry at her for this won't fix all the other things you have to be angry about and, in this instance, is misdirected and inappropriate. Resenting the fact that Ashley wanted to include her in this is basically resenting your mother's happiness and Ashley's. I'm going to guess that resentment is a lot more about feeling like you didn't grow up with the mother you wanted to have and you aren't getting pregnant in the way that you wanted. None of that is Ashley's fault and the first part, while it might be your mothers fault, can't be addressed through getting angry about her becoming a grandparent. She absolutely should see her grandchildren as equal. Anything less is unfair to her grandchildren and won't actually change the wrongs you experienced when growing up with her. She can't make up for the way she treated you by mistreating other children and I think if you really think about what you are expecting of her you will see that. You said it yourself, you finally have a mom who is a normal person, who is capable of maintaining adult relationships that are healthy. Instead of seeing this as an opportunity to mend your own fragmented relationship you seem to resent her for building health relationships with other people. You can't have that both ways. Either you have a mom who is loving of others (and therefore cares for all her grandchildren), or you have a mother who isn't capable of loving appropriately. Which mother do you really want? You're so clearly jealous of Ashley, and resentful with and angry at your mother. It isn't their fault that your husband's parents aren't around, it isn't Ashley's fault that your mother wasn't around when you were growing up, and it is absolutely not Ashley's child's fault. This kind of response is only going to negatively impact your relationship with both Ashley and your mother and, eventually, your children's relationships with their Aunt, grandmother and cousins.

It is time to work through your anger and resentment at your mother and detangle this from the issue of future grandchildren. I also would hold off on worrying about the name issue. Wait until you have your children and meet them. See what they want to call their grandmother. See if the realities of being a grandmother actually are what your mother wants (in some ways, Ashley having children first is an opportunity to see how your mother handles the not fun parts of being a grandmother). Nothing, not even a close relationship with her future grandchildren, is going to "make up" for how you were treated by her in childhood. It is an incredibly heavy burden to place on any child to expect them to right wrongs from long prior to their birth or heal lingering family hurt. You need to do that work on your own if you want a healthy relationship with your mother. It is understandable that it feels more comfortable to get angry about this than it would be to actually unpack and address all the things you are really angry about, but as long as your anger is directed towards this you're going to come across as unreasonable, resentful of Ashley, and out of touch. Nothing you described in your OP that your mom is doing is wildly inappropriate or wrong. Your reaction to your mom's excitement is, on the other hand, far more extreme than the situation calls for. It makes sense given the miscarriage, struggles getting pregnant, and anger you still have directed towards your mother. But don't make this representative of all of that. It comes across as petty and resentful of Ashley and her child and it isn't going to solve any of the actual hurt and pain underlying your reaction. You're doing yourself a disservice by challenging your feelings into this incident.