The question is: if you had 90 days left to live, what would you do? The answer to this question is telling of a person's priorities in life and what they consider innately good, an ends in itself rather than a means to some goal to be achieved in the future. If you had 90 days left, would you stay at work? Start to learn Spanish? Start exercising more? I doubt it, because these are all means to a ends, not ends in themselves. The means are meaningless when they are divorced from their ends - in this case, through random death in 90 days. So what are the meaningful things in life? What are the things we would devote our last 90 days to? What things give our life meaning, or - what is the meaning of life?
Back to the original question, what would you do if you had 90 days to live - A couple years ago I could not have answered this question without great deliberation. But then my daughter was born and now without a second thought I would reply that I would spend the time with her. I do not think it coincidental that any parent would respond the same. Similarly, ask any parent what their proudest achievement was and the most accomplished person would reply that it was their children, the only thing that is unconditionally good and worthy of love.
If this is true and children are the only unconditionally good thing in human life, what does this portend for any examination of a singular meaning of life? I would argue that the meaning of life is self-evident and is imbued in every human being by nature. The meaning of life is to propagate and then put forth every effort to make the life of your children the best it can be. In the theoretical context of evolution this makes perfect sense, and this is something that every parent already knows - from the moment your first child is born you know that your life is no longer your own, but belongs to them.
Basically, the question "what would you do if you only had 90 days to live" is not a question of what you would do but about what you value in life, and as humans we all ultimately value the same thing - family and more particularly our offspring. So I would contend that this is the meaning of human life.