I don't find the card particularly odd. In the past we've sent cards from the ward, but then it sounds like relationships were strained so possibly not something they would do. The parents must have told them when the funeral would be, when we've been invited to a funeral and nobody's been able to go, we've sent a card. Maybe other nurses involved that night were able to go and she's the only one who couldn't? In that case I'd think sending a card would be fine.
The comments about the mum wearing a short dress were ridiculous, she's clearly in a separate bedroom with the door closed. But then her college replies 'OMG' so clearly a few of them were bitchy. Also noticed lots more messages sent from others to her talking about work, whereas earlier it seemed she was the one initiating the work chat, so seems they all messaged about it