Well, the answer "Cecilia Kedrowski is Polish and Joseph Kedrowski is German" doesn't really get to the bottom of the question. The country of origin, as stated on a US census record, can bemisleading. The information can be flat-out wrong (for example, if the landlady or another mistaken person is the informant) or can reflect changing political boundaries, a sense of ethnic identity, and so on. A person can be born in a certain European town that is in a different nation, depending on the year you're talking about. On the census, a person might state the country as of the year they were born, or as of the current year when they were answering the census, or might not think it through that carefully to begin with.
The OP will need to discover more about the ancestry of each of the people he mentions to find out if they are related. They probably are.
Below, is this Vincent Kedrowski, who lived in the same place - Morrison county, Minnesota - from Poland, or from Germany?
from Find-a-Grave Vincent Theodore Kedrowski Birth: 1865, Poland Death: Mar. 28, 1943, Morrison County, Minnesota, USA Burial: Sacred Heart Cemetery, Flensburg, Morrison, MN "Vincent was born about 1865 in the portion of Poland then controlled by Prussia (Germany)."
more about Vincent from Find-a-Grave: John A Kedrowski Birth: Oct. 22, 1894, Poland Death: Sep. 10, 1978, Little Falls, Morrison County, MN Burial: Sacred Heart Cemetery, Flensburg, Morrison, MN Father: Vincent Theodore Kedrowski "John was born in the western portion of Poland then controlled by Pussia (Germany). He emigrated ca. 1895 with his parents and sister to the Minneapolis area."