The Irish Department of Justice and Equality provides a page where you can check the requirements.
By entering the details you provided in your question (Indian citizen, transiting in Ireland) you reach this page. The headline "You do not need a transit visa" is unfortunately misleading in your case, as the page lists further conditions which apply to transfers at Dublin airport.
Transit passengers making connections at Dublin Airport should be aware of the following:-
- You should check to see if you need a Visa/transit Visa before travelling and apply if required
- In all circumstances you will present to an immigration officer.
- Unless your arrival flight is in Terminal 2 between the hours of 0400 and 1600, you will need to go landside to make your onward connecting flight. This requires that you seek permission to enter the State (you will need to have the appropriate Irish entry visa if you are visa required for entry to Ireland).
Specifically the third bullet point is relevant for your friend - if her flight to Dublin lands at Terminal 1, she will have to seek permission to enter Ireland. That means she will require an entry visa for Ireland (not a transit visa).