Taken as a whole, the Guardian account paints the picture of a raid on the Syrian border on an identified target at which civilian casualties were also inflicted. That is probably what happened.
Of course, this conclusion is reached not only by reading what the accounts say, but also by inferring what they do not.
Update: More analisys is here:
If it is true that [according to Iraqi tribal custom] the women and children sleep in one place and men in another, then the bomb hit the tent with the men. The women and children may have been killed in or as they emerged from the villa which was the subject of an infantry assault.