Reintroducing could lead to problems.
Hmmm...could be...if she is really broody, and a driven mother (which she seems to be) this may not be the case. I would get to really know her, and also perhaps start building ground hid boxes she can defend the entrance to with a good peck (does well in keeping the snakes out as they don't push it when they are faced with a sharp beak peck to there very sensitive heads. I have used these types of ground boxes for several species of ground nesting Avids.
Incubation isn't an option being as I live off grid.
Well...that doesn't mean you can not have an incubator...as there are several both solar cell with deep cycle battery, solar water, and even antique methods that use wood fired modalities. Which I would consider if getting back into Avid Husbandry just to support the core of my mother with "success" in their endeavors to raise there own young....and...to keep my own full range of husbandry skills viable.
You think letting all the babies die is the best option?
Absolutely!...The laws of nature are not always to our human liking or understanding...yet...to anthropomorphise our own efforts in permaculture is to inhibit us from truly understanding all its glories as well... She (or hen Guinea) has a life she is trying desperately to live...you have (unwittingly) brought her as much distress as if she had battled a fox or snake and lost...either way she has suffered a loss...just like any other mother would...this can lead to depression and may even render her a poorer booder because of it. Now some would suggest that I am now "anthropomorphising" yet I believe we all have foundational ethologies and must be "strong enough" to except we do not hold superiority over all the emotions one may feel...or to what degree. Often what we think is "helpful," in the larger scope of things...it is not.
I feel humans influence has messed with the natural cycle so much that these decisions are necessary and conflicting.
Yes...they do seem conflicting at times...sometimes they are...sometimes (often?) we are injecting ourselves and our beliefs...for the better we hope, but not always.
Good luck, and much success to you,
j