Bernice King, 33, and her daughter Angel Harris, 14, were killed in the fire.
King was able to get all seven of her children out, except Harris.
Police said the suspects used Molotov cocktails to ignite the apartment, located in the 5800 block of Kennedy Terrace in the Lakeshore Dunes complex.
"You have an accelerant and you have a fire that burns real intense," said Gary Fire Investigator Stephen Johnson.
Police say the attack was fueled by a dispute between the two men and King's 18-year-old son over an XBox video game.
"There was a dispute over the XBox on Tuesday afternoon? Wednesday night the suspects came back and set fire to the aptm," said Gary Police Detective James Nielsen.
On Thursday, family members laid King and Harris to rest and expressed their gratitude over the arrests.
"They promised me they would do this and they kept their word. I thank them very much," said relative Janice King.
"I was there when everything happened. I just want to say thank you to the people who let us know who these people were," said relative Michelle King.
King is remembered as a hard worker.
"She was shy. She was always happy," said relative Linda Singh.
Gary Mayor Karen Freeman-Wilson praised the community for coming forward with information on the suspects.
"That's a good thing. That's the type of thing we want to encourage," Freeman-Wilson said.