Key point
One rule
Pick the boring stack you can ship, debug, and explain. A weekend project is judged on whether it works and can be reviewed, not on how many tools you used.
Your stack must let you build a UI, call your own API route or backend, and store or handle the data your app needs.
Weekend-sized means small
A good hackathon stack has few moving parts. You should be able to run it locally, make one change, and understand where that change goes.
For many college projects, that means one full-stack framework, one styling choice, and one database or mock storage choice. Avoid adding mobile apps, queues, microservices, custom auth, and admin dashboards unless the problem truly needs them.