maybe just be like "hi nice to meet you too but im looking for some peace and quiet on my way home. we'll have to chat next time instead!" and then like....lie back and close your eyes or open a book if you have one or something.
did i understand your scenario? is this what you were asking in your post?
I know English isn't your first language; I can't understand what you want other than the first sentence. I'll answer that one for you.
You answer: "Hi, nice to meet you too." Maybe with a handshake.
Nod, and say thanks.
Just tell them you have to go because there's a cat in your house and you don't have a cat..