Unknown : A Search with an old man

Yesterday night I had a dream. I mean I have dreams all the nights, but this was good. Very few times I have an inspiring dream.
It started with usual environments and people. I was going to ATM to collect some money, which I am going to do now and which I had planned to do since 3 days.
Then in dream, I found that the ATM is not working because of unknown reason. And I was accompanied by an old man in the ATM center. Then an unusual thing happened. The security of ATM told us(me and the old man) that take the elevator and go to top floor to collect the money.

Now I have no idea why sometimes these kind of things happens, an elevator inside ATM center is very unusual idea. So we took the elevator anyway and it took us upwards.
Now is when the story starts.
Upwards, when we reached, I saw that we have reached on the roof and the roof was a garden.
Actually not full flowing garden, but looked like an old wooden house which has become old because of wear and tear. Old like the old man. I suddenly realized that there is a connection between the old man and this place.
While I started walking around the place, the old man seemed like searching for something or someone. He was looking for his wife. She was not old like him because she wasn't there. She wasn't alive at all.

Here my actual dream ends but I am continuing it in the story.

I started thinking that why would he look for someone who is not alive. Or why would anyone look for something that does not exist. We never look for things which were in past. But we certainly look for things which don't exist but may exist in future.