The middle of the third game has Sonia's song in the third game. They basically added lyrics to the main theme, Shooting Star. It's very obvious that she's singing about Geo, considering it's a about a shooting star who guides her and always bring light to her path. Note that this game is called SHOOTING STAR Rockman in Japan and Geo has been her first friend.
The ending of the third game has the biggest heartwarming moments of all. After destroying Meteor G, Geo is left stranded in space with no way to return home. His father then spreads a message across the entire planet to wish for the safe return of his son, who had done so much for the world. This results in every single person in the world forming one giant brotherband with the purpose to "bring Geo back home", with everyone pooling their resources in attempts to find and retrieve him. Omega-Xis and Kelvin then use what energy they have to transport Geo back home, where he's welcomed back with open arms and celebrations. Jack is shown to have become friends with everyone again, and Ace and Acid are shown to have survived his Heroic Sacrifice, being tended to by Goodwell and Tia. Then, two weeks after Geo's return, Omega-Xis and Kelvin finally return as well, finally reuniting the Stelar family after so many years.