If a call would just open the gates to abuse and stress, then don't call.
If you feel like her Bday must be observed, then how about this....
A local pantry I go to offers the children of clients birthday boxes when their birthdays come around. In it is a cake mix, a can of frosting, some balloons and candles. That way, people who already have it pretty rough don't also have to kick themselves just because maybe they can't afford that stuff.
Maybe you could donate some stuff like that? Just a thought....sometimes doing something in honor of someone, but not necessarily FOR someone, is a good choice too.