Stanisław was born as Stanisław Mucha in 1854, in Solca Wielka parish, in Gębice. He married (1882) Konstancja Sybilska. He changed the family name to Muszyński sometime after he married.
I'm not certain why he did so, but it appears that his grandfather was born with the name Muszyński in 1806. It may be that the two versions of the name were used interchangeably.
It appears that all of their children were born with the name Muszyński(a) in Ozorków.
Franciszek Muszyński (1884-1960) m. (1912) Władysława Kępska in Ozorków
Anna Muszyńska (1886-1934)
Władysław Muszyński (1888-1941)
Bronisława Muszyńska (1890-1891)
Wawrzyniec a.k.a. Wacław Muszyński (1893-1943) died 21-07-1943 in Oświęcim
Stanisław Muszyński (1895-1964)
Janina Muszyńska (1898-1996) m. (1922) Franciszek Sibilski (1885-1940) in Detroit
Marianna Muszyńska (1900)
Stefan Muszyński (1903-1980)
Edward Muszyński (1908-1942) died somewhere in Russia
I've included a printout of the family, with all the data I have from myheritage.com.