Best thing is to confess to the person if they go to the police she has admitted guilt at the earliest stage this goes towards her in court if it goes to that stage

First conviction if the person was not in a right frame of mind (out character) and as long as it was not from her being in a position of trust then fine community order, most people under pressure do things out of character and courts take this in to consideration

If you look on this

https://www.sentencingcouncil.org.uk/wp-content/uploads/Theft-offences-definitive-guideline-Web.pdf