A basic claim to free nappies or food at reduced prices does not exist in Germany.
If you are entitled to unemployment benefit II or to social assistance, you can receive help for your livelihood if you cannot adequately cover your need for food, shelter, clothing, household effects, etc. This includes an initial equipment for babies. For the conditions for claiming a living allowance, please contact the Employment Agencies or the responsible social welfare offices in the federal states. Employment agencies close to where you live can be found at www.arbeitsagentur.de/privatpersonen. The responsible social welfare office can be found at http://www.sozialaemter.com/.
Social welfare offices Baden-Württemberg: http://www.sozialaemter.com/index.php/sozialamter-in-baden-wurttemberg/
If you are entitled to social benefits, you have the option of receiving groceries for your daily needs from the “Tafeln”: http://www.tafel-bw.de/mitglieder.htm
Church facilities help as well, if you need help.