I don't blame the police - 3 hours doesn't seem a massive period of time. It also occurs to me that finding the mother's name & address may not have been straightforward - after all, daughter probably *knew* her mum's address - so may not have kept it written down anywhere easily accessible - and if all you have is an entry in someone's phone saying 'mum' that doesn't help much (as PPs have said, the police would generally break this kind of news in person.Yeah but when the cell phone rings and the police answer to hear it is mom it seems like they could say something better than that somebody will be around.
The 'friend' who made the post was incredibly thoughtless.
The police might not be able, due to regulations, to announce a death over the phone.
One of the linked articles mentioned that the woman died in a friend's apartment. I now have this image of someone, whose friend was just found dead in her home, rushing to the computer to post the news on Facebook. Or immediately turning to her phone to get the news out. Seems an odd way to deal with a death, if that is what happened. (I don't know who posted the info, but this seems like a logical chain of events.)
I think people should wait before posting news about other people on social media. And while I cannot blame the police in this instance, given that social media are here to stay, it might be a good idea for them to review their policies about informing families about deaths, to see if there is any way they can shorten the time needed.