When the women are alone anything goes but the Qatari women dress very elegantly. I'm no aficionado but I would suggest something elegant but not overdone. A semi formal evening dress with high heels and hair done up a bit. Remember that whatever you wear under the abaya has to be comfortable with the abaya on. As for something to take - don't feel pressured - the Qatari's are dear people and the gesture counts more than the price of the gift. Take something that you would appreciate receiving. Just relax - you'll enjoy it I'm sure.