It is hard or nearly impossible for children to grasp the permanency of death or the permanency of anything really. Ariana was 6 when Thomas died and for months she would ask, "Is he really never coming back?" I think somewhere in her, she feels that after enough time goes by, he'll just show up again.
She's 8 now and was for some reason talking about going away to college and my mother was telling her we'd visit her and she'd visit us and she asked if her dad would. Had to tell her no. We're a Christian family and she's learned the 91st Psalm, and knows about guardian angels, but in our case, it's best I not complicate it with the concepts of angels and visions and visitations. I know that wasn't what she meant. We've had that conversation too. She asked if he was watching over us. I told the truth. I don't know. "GASP!" She's still at an age where me saying those three words is a shock. I figure I'll know everything for another 2 or 3 years, then I'll know nothing. Ain't parenthood grand?
I try to read where I can on how to help her. There's a lot of different advice. You can spend a lifetime reading about this. I think all we can do is keep a constant communication with them and when they ask about the parent coming back, be honest as painful as it is, using words they might understand. I've read they will develop an understanding over time and grieve in cycles which is something I have observed in my daughter.
Originally I told my daughter that some times when people get hurt or sick the doctor can't fix them and some people live like that, others don't and their bodies stop working and all they can do (because we are people of faith) is go to be with Jesus. In our case it was the heart and lungs and my daughter is old enough to understand you can't keep going without those.
I've stuck to my story, but still I have had to repeat it several times. And I think she feels Thomas is doing what he did here where he is. I still get asked if he eats, drinks, needs his TV, etc. I think she understands he can't be here (on any given day) but thinks, okay, he's with Jesus, he should be able to do stuff he likes to do. After all, Jesus is so wonderful right? I'll let her have that. I won't mess with what she feels her father is doing where he is. How do I know anyway.
I've learned to be prepared for a lot of repetition, to get asked the same questions over and over perhaps with months in between. It's hard and I'm glad we have each other, and I'll admit some days I wish it would sink in for both our sakes, but then I still have days when I want to believe he's just going to come bouncing through the front door again myself.