You'd have to damage the ship to the point where it isn't sustainable for a long term trip. Just maybe some short range things or whatever. Which isn't that hard if they stick to being low on resources, spare parts and what not.
Or, if they had been in another galaxy they wouldn't have even been able to push in the direction of home because they'd have to cross a 100,000ly void with no stars and no civilizations to stop and replenish supplies with.