It's hard to sit back and watch someone struggle if you think you can help, but don't forget that she is the treasurer. You'll help her more and build a better relationship with her if you work together to resolve the issues, rather than taking the books yourself. Your bookkeeping experience can be an asset to the PTO and probably help her be a better treasurer, if you take the time to teach her and review the books together. If you want an outside, independent resource, you might want to order the Treasurer's Toolkit binder from this site. It covers the gamut of treasurer how-to, including budgeting.
I believe "taking it" from her is not the answer. I'm sure she is not trying to frustrate you but do her job. I would give her a deadline, offer to review it for her, or let her go to a trained professional to figure it out. I would not ever suggest taking someone's job away from them unless they were given every opportunity to complete the task on their own first. Being upper handed will definately cause problems within your group and I do speak from experience.
The irony of commitment is that it’s deeply liberating-in work, in play, in love. The act frees you from the tyranny of your internal critic, from the fear that likes to dress itself up and parade around as rational hesitation. To commit is to remove your head as the barrier to your life. --Anne Morris
I am new prez and our new treasurer is having trouble going forward with the past treasurer's figures, they are not balancing. She is becoming very frustrated and I offered to take everything from her and look at it myself. She is not giving me the info I want. As pres. do I have the right to take this info from her and from last year and try to work it out myself without hiring a CPA. My husband does financial analysis all the time and I am a bookeeper of 20 years. I hate to be bossy, but I know I can calmly work this out and if not I have a great repore with the past board. What do you think?