What can I write?

[biscuitsfordinner]

Some old friends of ours lost their 15 year old ds earlier in the year. He died of an aggressive cancer after a fairly short illness. Throughout it all their DM (the H's mum) was a rock and two weeks ago moved the length of the country to be nearer to them and her other children. Two days ago she suddenly passed away.
She was really wonderful lady who was devoted to her family. I can not begin to imagine the pain they are all going through.
I have started to write a card but all my words sound so hollow in the face of such a devastating loss. Can anyone help me please?
Thank you

[BirdintheWings]

Sort of what you've written there:
'I'm so sorry for your devastating loss of your wonderful mother. There are no words, but I'm thinking of you.'

Just don't do what DH did, and worry so long about the wording that you never send the card.