Despite the query's assumption, the Marilla Historical Society is located in Marilla, Wisconsin—a small town in Marathon County, central Wisconsin—not New York State.
"Marilla" appears in New York (Marilla, Erie County, near Buffalo), but that community's historical society operates separately as the Marilla Historical Society of Erie County. Two towns, same name, different states.
Contact via Marathon County Historical Society (Wausau) for current hours and research access. The Wisconsin society welcomes genealogical inquiries from descendants of early settlers (predominantly German, Polish, Norwegian).