Edna and her husband were really great hosts! They were very nice, helpful, friendly, down-to-earth, and had a great sense of humor. They gave me information about places to checkout, how to get around, and were on standby in case I ever got lost or had any questions. They live in a large apartment complex in a safe neighborhood within walking distance of UNAM (it took me no more than 20 minutes to walk to the Facultad de Quimica/Facultad de Medicina). Copilco metro station is very close to the apartment (~5 minutes walking distance). And there is a bus (across the street from the apartments) that can take you to the center of Coyoacan in ~10 minutes for only 4 pesos. A taxi from their apartment to the Mexico City airport costs about 120 pesos and takes ~30 minutes. There is a 7-eleven store right on the corner of the street, which was very convenient. I would definitely stay with them again and I look forward to meeting up with them next time I'm in DF :)