Please can someone help I'm asking for someone who wishes to remain anonymous

My friend for reasons she doesn't understand used to have a shop lifting addiction that unfortunately coat her two jobs she has no idea why she did this and is trying to turn a new leaf and become a better person. Unfortunately recently her father had 100 pounds [100) go missing from her bag and she swares she's completely innocent and hasn't taken it but he isn't convinced due to her past what can she do? There is no evidence of her taking it or anyone else taking the money it just disappeared from his bag

She's heartbroken he blames says he's doesn't trust her but she understands this given the past but it still hurts and unfortunately this isnt the first time money has gone missing, what should she do?

If anyone interested she's never stolen money when shopping lifting in the past it was mainly food/beverages like a can of soda or chrips or sandwiches aka groceries .

Update: he's "blaming both" my friend and her mother and says he hopes the person dose the right thing and returns the money and my friend mother is crused that her daughter (my friends) getting blamed and friend is terrified that they'll break up due to this