Ending of In The Time of Butterflies

Reading the end of this novel really gave me an insight as to what exactly happened the day of the three Mirabel sister's deaths. The story ends with Minerva's last narration on November 25th. The epilogue lets Dedé to continue the story.
The story has it that the women were traveling down a road with their driver, Rufino after visiting their husbands in jail, a jail they were purposely moved to because the SIM knew they would have to travel down that road. This specific road was where the sisters were murdered and then placed in the old Jeep, and pushed off a cliff.
Like Alvarez, I wondered why this happened. Did the girls know they were to meet the face of death that fateful day?
"It is the sweetness that makes them burn." While Alvarez's character Dedé was talking about sugar on page 320 here, I realized that this could be a reason as to why the Mirabels risked their lives that tragic day. To elaborate, the Mirabels always knew their lives were at risk, especially after starting the underground and being so actively involved. I'm sure they all knew eventually, their "luck" of being alive would run out. They knew their husbands were in trouble in the jail; the sisters were willing to risk that to see them one last time. I'm sure they had premonitions the roads could be dangerous.On page 297, Alvarez states through Minerva that " ...it was as if we were girls again, walking through the dark part of the year, a little afraid, a little excited by our fears..." To me, this means that they knew there could  be a chance things could change on their journey home, obviously doing so. What I realized, despite the unknown, was that they came so far in the revolution, changing lives in the sense of involving others to fight what was right for their country of the Dominican Republic. They were role models for women to come, proving women are strong, have opinions, and can fight for what they find important like the Mirabels did. They came so far... why not go all out and "fight" till the end? On page 302, Alvarez states that Patria's last words were "Tell the Mirabel family in Salcedo that the calíes are going to kill us!" I think the Mirabels felt they came so far with their underground revolution, they should be strong and fight till then end. They knew their chances of being murdered were high, yet they stuck to their morals and continued to meet with their husbands. It was their greatest honor because they were all in it together, and they knew they would leave this earth happy they succeeded great things.
While this could be one possibility as to what the Mirabels did what they did, I think the answer speaks for itself. They truly fought till the end.