Grouchy old people on the bus are nothing new (in fact just being on the bus in the first place would make anyone grouchy, but this old lady takes the cake.
Let's be sensible, people. Once someone has had six children, especially if she lives in the US or any other developed western country, a few things should be clear to you:
1. She has had plenty of time to figure out what causes that.
2. If she owns a television or has a doctor, she has probably heard of birth control.
3. If she has had six kids she has probably chosen not to use it.
4. After six children it's a little late to be lecturing her. If you don't like large families, talk to people about it before they have them.
5. If you think someone is trying to "take over society" by outbreeding you, it is your civic duty to keep up. Otherwise, you have no right to complain.
Motherhood is not a disease that needs to be cured, and children are not a plague.
Related: A fun t-shirt for parents of large families.
Note: Somehow the link to the article about the lady in question was directing people to a page about Emily Dickinson. How this is possible, I do not know, as I have never seen that page, and I am sure that this post originally linked to the article. The error, in any case, has been corrected.