Further ask yourself who put her in that place what was the proximate cause - the answer is the phone call of the two idiot Australian DJs.
That really is speculation. I doubt very much that it was the Australian call itself that caused her to suicide. It's a suicide. It isn't something she decided to do just because somebody said "boo" one day. There will be a whole lot of complicating factors around her decision to take her own life, and the prank call will only be peripherally involved.
If you want to trace the acts that led her to that decision in the very long term I would bet you dollars to donuts that she was already suffering from depression and the people and institutions around her either failed to see it, or failed to respond effectively.
In the very very short term, in the minutes and hours ahead of her decision to kill herself, I bet there were negative interactions with people in her workplace, negative implications for her job prospects, loss of respect from her co-workers. While these things may have ultimately been reactions to the story in the media, they are likely MUCH more about the culture and relationships already in place in that hospital prior to that phone call even happening.
There isn't going to be a simple answer to why she killed herself. People get pranked all the time and they do not suicide. A lot of teenagers get bullied the way Amanda Todd did, but they do not all go on to take their own life. There are personal and environmental factors there that are MUCH more significant.
What you should really be asking is, what could change, that might have prevented this woman from taking her own life.
Absolutely, with certainty, I can say that the answers to that question will all be found in her personal and work relationships, and will have nothing whatsoever to do with media policy in Australia. Most of them will relate to the culture in that hospital, the availability of resources she could have turned to, the ways in which conflicts are managed there, and quite a lot, maybe just how well we do at helping people in our society develop meaningful friendships and family relationships.