It looks like all the old teammates of Sam somehow hate him. Well, Sam is aware of that. Because of this, even though he already noticed Lily and the others, he did not try to talk to anyone.
At this time, while Sam is present inside the restaurant, he did not know that the person who wanted to kill him was already looking for him.
It looked like that person wasn't alone. Another person was to decide on him and both of them are currently observing Sam's house.
Naturally both of them are not idiots who will attack Sam's house like that. First of all, that house is close to the Golden Dawn Academy.
Also it is present inside a security area and even trying to invade that house is impossible. Because of this, both of them observed the house and wanted to know about the current location of Sam.
Even if they did not get the chance to attack Sam, they also had a task to kidnap his students.