Walt Disney World Transportation bus service (which is operated by Disney) to WDW resorts continues until all Disney hotel guests are out of the park. At some point, after most guests have departed in the usual way from their usual bus stops, buses continue to be dispatched on an as-needed basis from the front of the bus area, with impromptu routes bases on where guests need to go.
The Hilton Orlando Lake Buena Vista Hotel does not offer Walt Disney World Transportation bus service. Instead, this hotel uses Downtown Disney Resort bus service (which is not operated by Disney)
You can always get to Downtown Disney via Disney transportation and walk over to the Hilton; it's basically across the street from the Marketplace end of DTD. Unfortunately, there are no buses between the parks and Downtown Disney, so you'd have to travel to a resort and then to DTD. Conceivably you could take a bus directly to Saratoga Springs and then walk to the Hilton, which is just down the street, but it would be a bit of a hike, like maybe 3/4 mile. Maybe a bit less.
In the unlikely case that the meal at AK takes so long that you are unable to catch the final Hilton bus two hours after park closing, you certainly have the option of using a WDW bus to DTD and walking to the Hilton or catching a Hilton bus at DTD.
Technically, there is no WDW bus service from any of the four major Disney theme parks to Downtown Disney. However, it's possible to to take a bus to a Disney resort, and then to take a bus to Downtown Disney from there. Also, it's possible that you would be accommodated with an impromptu stop at DTD if the park has been closed more than two hours.
Depending on whether you would walk for catch the Hilton bus at DTD, you would use a different DTD bus stop. Just ask the driver.
Y'know, come to think of it if you take the Saratoga Springs bus and get off at the stop closest to Downtown Disney (which I believe is the Congress Park stop), you'd cut the distance to your hotel to less than a half mile, which isn't that bad a walk. It would be like walking from Raglan Road to your hotel, which is easy-peasy. Given how crappy the Downtown Disney Hotel bus service is, I might be inclined to use the Saratoga Springs busses every day.
And let's not mince words: the Downtown Disney Hotel bus service is not great. Lots of stops, slow, doesn't come nearly often enough. Avoid it if you can. Disney bus service isn't perfect, but it's much better.