In case you don't have this, there are AMBERGERs buried at Calvary Cemetery in Petersburg, Menard Co IL. ANNA C. AMBERGER b 1876, d 1940; JOSEPH C. AMBERGER b 1876, d 1951; LUCILLE AMBERGER b 1914, d 2002; and THOMAS P, AMBERGER b 1911, d 1996.
Also, don't know if this is same JOSEPH as above, but on 1880 St. Louis MO census: MARCUS AMBERGER age 36, b Hungary, clothing merchant, wife HENRIETTA AMBERGER age 28 b Prussia, JOS. AMBERGER son age 6 b IL, ALEXIS AMBERGER son age 3 months b MO.
If above ANNA & JOSEPH are yours, the public library in Petersburg should have obituary for both as well as for THOMAS, which should also give info of A & J's children.