A Baldwinsville, New York resident, Mercia Grant worked in Boston with the Metropolitan District Commission’s payroll department. Her current activities focus on the philanthropic and include support of the Ancient Order of Hibernians, a Christian fraternal organization. Mercia Grant is also a contributor to the Liverpool High School Warriors Marching Band and supports suicide prevention initiatives as a way of honoring her grandson’s memory.

Ms. Grant has long been active with the American Legion and is a supporter of charities such as Paralyzed Veterans of America. She is also a longtime contributor to the St. Joseph's Indian School and to St. Jude Children's Research Hospital.

A cause close to Ms. Grant’s heart is research and awareness-focused activities related to Sudden Unexplained Death in Childhood (SUDC). With her granddaughter Lily Mercia Sateriale having failed to reach her second birthday before succumbing to the condition, she has volunteered as a planning committee member for two events in the child's honor. The first fundraiser, Lily's Walk for Answers, was held in 2012, while the second, Lily's Irish Party, took place in 2018. Mercia Grant’s efforts helped raise money both for the SUDC Foundation and an SUDC program managed by Boston Children's Hospital.