Kathryn Grayson

1. Is she still alive?
2. How can I write to him?

A1
Yes, she is alive. It has about 86 years now.

A2
This is his official website: http://www.kathryngrayson.com/
Maybe you can write to the webmaster and ask him the way to write to Kathryn. This could be the fastest.

She is still alive. You should be able to find something you need to know about her here:
http://www.kathryngrayson.com/

Very nice voice, just saw her in a film of Andy Hardy some time ago. Good luck contacting her. Peace.