I am a midwife and I've worked extensively in the Philippines (not Laos, though). There really are not any foods to avoid after giving birth. Of course, if a particular food makes you unwell or is rotten or makes your baby sick through your breastmilk, you shouldn't eat it, but other than that it is fine to eat pretty much anything! Cow meat should actually be a good thing--it is high in iron and protein and helps to rebuild the body after the stress of pregnancy and childbirth. Your mother's concern sounds more like a superstition, I'm sorry to say. There is much more possibility that your aunt could have acquired an infection during the birthing process (particularly if she gave birth at home or in less than ideally clean environment). Or may have eaten some contaminated food. If it is an infection, she should definitely get a prescription for the right type of antibiotics, because it is quite common for women (especially in poor or developing countries) to die from infections following birth. Are you sure she is unable to see a doctor? I would highly recommend it. If it is an infection, it is nothing to fool around with! I hope she feels better very soon!