I'm not sure the OP meant to question the faith of the people on her FB feed, but merely their response which seemed to her to be rather thoughtless and short sighted. In some senses I'd agree with this. I'm a Christian and have my own stories to tell of prayer/healing/non healing, but I think I should be careful how I word things - if a child has recovered, I'm careful to acknowledge the doctors, nurses, the sheer commitment and knowledge of those who have cared for the child. I thank God too, but am careful how I do this; I do not thank God in a smug 'you healed this child but not that one, praise you' kind of way, but more in a slightly uncomprehending 'I know you love this child; I know you love this other child who has died too, and I don't get it' kind of way. A way that is real.
I'm so sorry to each and every one on this thread who have told of the loss of their much loved ones. The pain is palpable and the anger - against Christians who use (sometimes) well intended but ill suited words, against God, against the idea that anyone would believe in a God - a God who would let such suffering happen. And I am right there with you, because I do not have a one size fits all answer to this.
I've experienced non-healing all my life; born with a degenerative disease which has robbed me of much and I've had my fair share of the 'just pray and it'll all be fine' type of rhetoric from some of my fellow believers. I sometimes find this incredibly hurtful; do you think I'm not good enough? God hasn't answered me because I don't show enough faith/say the right words? I find this hurtful from people, but all I experience from God is this all consuming love, this containing of me in my suffering which is inexplicable and profound, this waiting with me in my pain, alongside me in the darkest nights where my lungs threaten to finally give up on me and my body shudders with the most hideous of pain. I ask for healing, in those times, and it comes to me in the form of peace, of knowledge of God's loving presence.
Far from thinking God doesn't care about those who die, I think God weeps too.
I know it's not enough, I know vague feelings present no empirical evidence. I know it. I've been round this a thousand times. But all I can present is what I have found, time after time, and that is the presence and action of a God who got involved in human history through Jesus, who got down and dirty in the squalor and who suffered in the ultimate way. A God who gets it.
I can't answer the question as to why some, and not others, seem to recover/be healed/whatever. I use the description of the now and the not yet - of these 'miracles' being windows on how it should be and once will be, rather than arbitrary examples of God's favouritism. Examples of what God intends for God's creation, a place where there is no mourning or death, where all those things have gone away.