It is not a flight attendants job to lift baggage. If you are unable to lift it yourself (sounds like it was too heavy to be on board in the first place), check it in, or put it under the seat in front. Don't cede responsibilty to someone else.
At 48kg, I suspect that Mrs Green's problem wasn't that the bag was too heavy but that the overhead bin was too high. Certainly that's the impression I got from reading the comments. Let's be honest, some packages can meet the legal limit of 7kg and yet the type of package and the size of the person means that some assistance is required.
Still, that attitude of 'it's not my job' doesn't surprise me.
