So sorry about your friend, Peonyrose. You are clearly a very kind and caring friend to want to help her.
Please don't beat yourself up about the fact that your advice seems to have backfired. No doubt, you had no idea how the D would react. In hindsight, if D wasn't answering texts or phone calls, chances are she didn't want a visit either. But for all you knew, perhaps she was just busy. You certainly couldn't have known she would blow up at your friend that way.
This could be a case of a D who bled her mum dry and then dumped her when there was no more money left to give. Or it could be that D has some longstanding issues w/ mum but chose to maintain contact as long as she needed whatever mum had to give. Or it could be more complicated than that, as some PPs (previous posters) have said. Hard to know from the outside, etc.
But it doesn't matter now. Your friend needs your support, as others have suggested. IMO, there's nothing "cold" about just listening and nodding, and maybe saying, "I'm so deeply sorry," etc., as you might for any other person who is grieving a loss. If your friend asks for advice, I suggest giving it in the form of suggesting activities and volunteer work, etc. that would fill her life more. Also, IMO, you could hold out the note of hope that PPs have mentioned, the GC will most likely contact her when they are older. As long as you stay away from advice on her relationship w/ ED (estranged daughter), I think you'll be ok. IMO, you're a great friend, and you will help her get through this.
Can You Name 5 More Songs? (number 2)