The Mammalian Diving Reflex (MDR) as it relates to survival in cold water seems to be related to how quickly a body loses temperature. Compared to adults, small children have a higher surface area to internal volume ratio, so they lose body heat more quickly. As the body cools, blood flow to the extremities is reduced to maintain blood flow to the brain, protecting the brain for the longest possible time. That's why children who have been submerged in very cold water for a long time have a better chance of survival than an adult. Adult body temperature drops slower, so MDR kicks in later, perhaps after brain damage has begun.

I don't know if MDR had any impact on earthquake survival other than how the body responds to hypothermia. Elderly people tend to be smaller and more prone to hypothermia for a variety of reasons. Perhaps the cold weather in Iran actually contributed to her survival. Perhaps she didn't need as much water and food to survive as most people. Perhaps she was just very, very lucky (or blessed by God, depending on one's point of view). Regardless, survival against such long odds is remarkable.