Both are correct. You can either 'help someone to do' or 'help someone do' something. If it's Rosa's own homework, it should be 'her' rather than 'the' homework, and remember always to use capital letters for names. Help Rosa check her homework or Help Rosa to check her homework are both fine.

It would be, " help Rosa check the homework" or "help Rosa check her homework" if the homework was done by Rosa.