I am making two assumptions here:

1) His "job has dissolved" means that there is no longer a position at his company for his role.

2) This expectation and promise of higher salary was made at the time of hire.

It sounds like your husband's company decided that they did not need the function that your husband or his teammate performed. They have known this for some time, thus the lower than expected raise (to avoid raising salary expectations for the inevitable transfer).

So, it sounds like you have two (or three?) options:

1) School: Loss of income, but the potential greater growth. Would his education actually bring higher earnings, given his field and your location?

2) Take the transfer at the company: Possibly less income, less seniority. But you would still have a reliable income. I am uncertain of any promises of future salary growth as he has already been denied that once (and was not told of company plans).

3) This 100k figure you are stating, is this with the internal transfer at his current employer, or is this a 3rd party offer?

He isn't being fired or laid off, so I do not know if unemployment insurance would apply here. You need reliable income, at least until you graduate and can produce income as well. In this position (barring a generous and firm 3rd party offer), I would stay with the current employer until you graduate. Once you have your own income coming in, then you will be better equipped to address your husband's education and/or career growth.