Answer: Post-traumatic stress disorder
Step-by-step explanation:
Post-traumatic stress disorder could be defined as a scenario where an individual experiences a bad situation in life, that they were affected by the situation. When experiencing such situation, their subconscious mind is affected, this experienced situation dwells in their subconscious mind and play back images of the situation especially when same scenario or something linking to that scenario wants to happen again. So, Mila's experience and her avoidance of going out could be summed up that she's currently having a posttraumatic stress disorder from the flood event.