I think not acknowledging her daughter's birthday, by way of text, phone call or card, is awful!! The last people you expect to forget your birthday are your parents. I'm not familiar with the steps and making amends, but would imagine that at the very least, since she's been out of rehab she could have at least sent one or two texts to her daughter, especially today. But, nothing, nothing at all. I'm afraid I don't see that there is any excuse whatsoever (apart from death) for forgetting your child's birthday.