This is really confusing, because looks to me like there are two threads going on the same subject, but I'll give it a try....
I'm still confused about how you are set up since apparently there are no bylaws or set meetings, but I think the money just needs to sit in your bank account until a lot of things are resolved. Unless the school's tax ID number is on the account and you are actually a subgroup of the school, I don't see how a school employee can just go in and take over the account. If you're independent, you must at least have some document on file with the bank showing how many signatures you need and who they are. Once new officers are in place, then they get to sign checks. Until then, I think your name just continues to sit on there. I can't say I've ever heard of a situation where someone goes in and takes all the signatories off an account and leaves no one on at all--I'm not sure the bank would even allow it.
I don't know how your group makes decisions on spending money now, but I wouldn't unilaterally decide to do anything with the money at this point if I were you.
As someone put in the other thread, it seems to me that the school is trying to help get this resolved by organizing an election to find people who are willing to take this on. I don't understand why, if you and the other 2 officers don't like the way the school did it, that you don't just draft a letter to organize a meeting and election, and get it distributed to parents ASAP? Just say, look, it's a new year, some people have been in their positions for a number of years, they are unable to continue. In order for XYZ parent group to continue to do the good work for our school that we have been doing, we need new blood. (Obviously, it would need to be worded a bit more eloquently, but you get the idea.) Then, if no one steps up, you can either leave the group inactive (with the money sitting in the account), or use whatever procedures you have to decide how to spend money to disburse the rest of it appropriately and disband the group.