one test for her to be a dependent under the qualifying child rules (see meets the other rules) in 2025 is that she must be a full-time student (under 24 on 12/31/2025). Full-time means she must be enrolled full-time for any part of 5 months in 2025. The question is whether or not she was a full-time student during any month in her internship. If yes, she's your dependent for 2025.
If she was not a full-time student during at least one month of her internship, she might qualify as a dependent under the qualifying relative rules.
the key rule here (the others are met) is that her gross income must be less than $5,200 for 2025
