How did the speaker and the old lady become good friends?

Some years ago I moved to the country. There were not many houses in the neighborhood at that time. The house closest to mine was occupied by a woman. She was about 60 years old and lived all by herself. I used to take a morning walk and on my way home the old lady would invite me to her house for a cup of tea. Soon we became good friends. We talked about a lot of things when we were together. But my neighbor never mentioned her family. It seemed to me that the old lady had no relations and her only life companion was her pet -- a dog she called Tommy. One night in July I was fast asleep when I was suddenly awakened by the harking of a dog. When I opened the door, I was surprised to find Tommy there. When the dog saw me, it started running towards the house of its owner, stopped, harked at me, and started running again. I followed the dog to my neighbor’s house and found the old lady was lying on the floor. Later I learned from the doctor at the hospital that the old lady had had a heart attack that night and that her life would have been in danger if I had not taken her to the hospital immediately.