What do you mean by "could have ended it"? Hamas wanted to make a deal to release the hostages since October 10th in return for Israel releasing the 5,200 Palestinian prisoners. The entire point of the hostages was to exchange them. Israel is the one that didn't want to make a deal. That's why there were so many protests within Israel to "return the hostages". Those protests weren't about continuing the war, they were about pushing Netanyahu to end it and make a deal