“Jesus strictly ordered them.
No one should know this.
He told them
To give her something
καὶ διεστείλατο αὐτοῖς πολλὰ ἵνα μηδεὶς γνοῖ τοῦτο, καὶ εἶπεν δοθῆναι αὐτῇ φαγεῖν.
The ending to this story is different in Matthew, chapter 9:26 than that of Mark and Luke, chapter 8:55-56, that are similar. Mark indicated that Jesus strictly instructed or ordered them (καὶ διεστείλατο αὐτοῖς πολλὰ) that no one should know about this incident (ἵνα μηδεὶς γνοῖ τοῦτο). That would have been hard because this was such a public event. However, Jesus told them to give the young girl something to eat (καὶ εἶπεν δοθῆναι αὐτῇ φαγεῖν). In Matthew, this event spread all over this land or district without any attempt to keep it quiet.