How do you get social security to do their job and coordinate with the IRS?

My daughter's husband died in February 2011, leaving 4 children behind, 3 of which he fathered with my daughter. She has applied for survivors benefits, received confirmation of what she should expect for 2 of the 3 girls, including a large 'back pay' check. This caused any istance benefits to end so her rent is now $1000 a month, but she has not received any benefits. Now SS is asking her to provide information from his 2001 taxes. They didn't even know each other in 2001. They said they can't proceed without this information. Why is it she is expected to find information they should be able to get by making contact with the IRS? What does she do now? She is 2 months away from not being able to pay rent. She needs advice. HELP!