Yes. Slonina and Stonina are the same name.
Teresa Slonina, aka Teresa Stonina was the mother of Mayor Anthony J Stonina of Chicopee, Mass. See Hampden County Registry of Deeds (on line, public search 2). Go to Book and Page No, then search for: (1) Book 1002, pg 282; and (2) Book 2314, page 418. Note: Katherine Pikula/Katherine Teresa Pikula was the daughter of Teresa Stonina.
Teresa's husband was Joseph Slonina.
Joseph Slonina of 184 Chicopee, St., Chicopee, Mass, died 6/2/1914. See image/record at familysearch.org.
Also see: Stonina, Teresa, arrived at New York on 10/27/1909, on the Kroonland going to husband Jozef SLONINA
in Northampton, Mass (family lived in Northampton before moving to Chicopee, Mass.)See lines 19-23 of manifest. View image at ellisisland.org.
Note: Joseph Slonina's father was Michael.