It sounds like she got the ongoing American Survey Form, which asks all the intrusive and illegal questions. Tell her to ignore it.
The 2010 Census forms will go out in March sometime and should only have 10 questions. There is no long and short form this year.
That Survey Form included many questions that needed data from the Tax Form 1040. It looked like a way for parts of the government to get around any IRS confidentiality rules.
I did tell her that she only had to tell how many people lived in the house. She’d already filled it in and mailed it out.