In most public libraries that I know of, filters have been instituted over the protests of the librarians. I know of very few librarians who actually think internet filters are a good idea, and most of them would be happy to have evidence of how these stupid filters adversely affect communication. So you might consider suggesting that your mom mention these incidents to the librarians. (It's possible that this is an exception to the 'librarians don't like filters' generalization, but it would be worth a shot.)