|Nina Krause, Leonard Krause, Robert Krause|
It contains no clues as to location. My best guess for time period is around 1895-1900. There are three children, identified as Nina Krause, Leonard Krause and Robert Krause.
Using census records, the only instance I see of children with these names in the same household is the 1910 Census for Bethlehem Pennsylvania.
KRAUSE, Edward J., head, 53, [born abt 1857],widowed, Penn., Penn., Penn., sales agent at Steel company
KRAUSE, Hortensia E., daughter, 27, , single
KRAUSE, Nina, daughter, 22, , single, teacher at a school
KRAUSE, Robert, son, 20, , single
KRAUSE, Edward Jr., son 7 
Interestingly, living right next door is another Krause family:
KRAUSE, Henry A., head, 49, , merchant at hardware store
KRAUSE, May (Mary?), wife, 46 
KRAUSE, Lenard R., son, 17,  illegible occupation
Findagrave website shows Robert P. Krause (1889-1941) buried in Bethlehem PA, a son of Edward John Krause (1856-1917) and Sarah Coleman Lee (1860-1892). His siblings include Nina L. Krause-Liebig (1887-1973), an older brother Albert E. Krause (1884-1932) and a few half-siblings. It also reports that Robert was a soldier in WWI.
The Findagrave entry for the father, Edward, reports that his parents were Robert Parmenio Krause (1830-1866) and Hortensia V. Weber (1833-1902). Edward was married twice, first to Sarah Coleman Lee, who died in 1892, then to Nina M. Lee (1864-1905), who very likely was a relative of the first wife. Among Edward's sibling's there is a Henry A. Krause (1860-1930) who is most likely the neighbor on the Census. Henry A. Krause's page at Findagrave lists wife Mayetta Roberts and only one son; Leonard (1892-1978) thus the Lenard (Leonard) in the photo is a first cousin of Nina and Robert, as well as next-door neighbor.
Further research shows that patriarch Robert Parmenio Krause was a son of John Krause and Elizabeth Beitel.
Leonard Krause married Mary Dech and the pair remained in Bethlehem for the remainder of their lives. Nina married John Leibig. I cannot find a marriage record for Robert.
Eldest daughter Hortensia, mentioned in the Census, married Frederick J. Schmid on Sept 12, 1912. The news was carried on page 1 of the Allentown Democrat the following day.