My son and his fiancée were trying to get into their own place with their daughter (they were staying with her parents) My son came to me and asked if I had any way I could help them out financially to get into an apt. I went out and got several installment loans with the understanding from them both that they would have to help make the payments. After she was given the money she broke up with my son and now claims that she had nothing to do with any of the money and is refusing to help pay back money she kept. My son has agreed to pay back the part of the money he wound up with. What are my options now?

File suit. Your son can testify that these were loans.

...with the understanding from them both that they would have to help make the payments. ...

It appears that she has forgotten the promise she made. Do you have anything in writing from her?

You can sue her on her verbal agreement. If the court believes you, you win. If not, you loose.

Were they able to rent the apartment? Who has it now?