I don't think its impossible - it appears she went home on a relatively regular basis. Maybe she was just really close to her mom? Living in NYC at her age, I'd think she would be out on the town most weekends. I know at her age I was loving the Boston scene. So maybe there was a dude.
Alternatively, I also wonder if someone overheard her plans for Sunday - i.e. "Going for a run before I hit the road" at a restaurant or something like that. I think she was with her dad the night before eating out.
She did go out to eat with her father the night before, yes. They went to the 111 Chop House in Worcester.
If someone did overhear her talking about jogging etc, the next day, I am thinking this.
The tables/booths at that restaurant, are spaced out, meaning not impossible, but hard to overhear conversations with people talking at normal tones. If she was discussing that with her father, I doubt she would have discussed times, because he would have known what time she went home to NY, and I would think that conversation would have been more general.
The bar however, is more crowded. If that's how it went down, I would think she may have run into someone that she knew at the bar. She may have gone into detail then, but It would have been hard for someone that didn't know her overhearing to know where she was staying, unless they followed her home., and he wouldn't have had much time to plan it out. I think the perp knew that path, and the chances of someone at the restaurant knowing all of her details, where she was staying, and knew the path, is slight.
I am not saying you are wrong, because this is anyones guess, just my thoughts.
Her Dad must have gone over that night in his head, and I would think if she was away from the table for a while talking to someone at the bar, he hopefully would have remembered that.