The student obviously needs to address the absence issues, beyond that unfortunately not much can be ascertained from the report card because of the attendance problems. My inclination if this is unusual for the student would be to question relationship issues as well possible drug use/excessive partying taking place and the student not managing that effectively.
Party hard, Party long, smoke weed or whatever but don't let it control you or interfere with school...If I were the parent (and do take in to account I do not have kids) I would definatly calmly talk to the student and see what is going on and make sure they know they have my support and do everything I could to encourage them to take the school work more seriously.
If they had a car, cell phone or computer I would probably take those away and allow computer usage only under strict supervision and lock down the computer and begin taking the modem to bed w/ me. I would also install camera's to watch them enter and leave and watch for them sneaking off.