It doesn't have to be peoples that we already saw. It could just be some old enemies of the Mikaelsons ( and god, they have many of them ) who seek revenge and could come after Hope.
The words could be spreaded that Klaus Mikaelson's daughter is in this school and it would draw old enemies of the family in Mystic Falls and the school. Some people could just want to kill her to get revenge against Klaus by destroying the most precious thing he had in this world, the person he died for. Or they would try to kidnap her so they could make a trap for the other Mikaelsons. And it may sound stupid, they could even get money from her. Season 3 of TO showed that a lot of peoples offered countless money and other things just for a tiny piece of white oak... Imagine what peoples could give so they'll have Klaus' Mikaelson daughter burried alive in their garden or as a prisonner to torture her.
When Hayley was pregnant and even after Hope's birth, they said countless time that Hope inherited all the Mikaelsons enemies and that she would probably never be safe, but this idea was never used.
It would make a good story developpement for Hope too because she never suffered ( or we never saw it ) of being a Mikaelson. Always having people who want to kill or make her suffer, causing trouble to anyone around her while she did nothing to earn this... just all the mess that her family did in their life that fall upon her and make her life hell. It would interesting to see her having a love / hate relationship with her family because she still and will always love them but sometime she would hate to be part of it.
Hope really have a lot of potential as a character, but I don't think Legacies handled her correctly this far...