In fact, this dream itself is very simple, but it is not too complicated.
This dream represents two meanings. First, your mother misses the past. I write to get in touch with something in the past, but I don't know the address, so I don't know how to communicate. This may be an anxiety that your mother's memory ability is declining.
I don't know the details. I hope you can tell me more about your mother's recent situation. In this way, I can give a more accurate explanation
Of course, the most accurate person to interpret dreams is your mother. However, there is absolutely nothing to worry about and care about in this dream.