Well I wouldn't, personally, though that would depend on the details, so a bit of clarification please - do you mean you froze your own, home grown broad beans from this year, or last year? Were they young or older and did you shell and blanch them first?

I wouldn't eat beans (or anything) that turned brown in the freezer.

Unless you blanch them broad beans do start to turn brown after a few months in the freezer... We just make sure to eat them fairly rapidly :)

If you decide not to eat the brown ones but there are still some green ones they do make very nice soup with a leek and finished with cream, creme fraiche or yogurt.