On the surface this question seems like a no brainer, but it can actually be trickier than it appears. The first inclination is to tell a child “of course she misses you.” But this can pose challenges to other understandings they have garnered about death and tends to backfire. After all, if she’s “right there with you” or “looking down upon everything you do” or “her spirit is visiting you from heaven” as parents also commonly say, why is she missing me? It’s a question with a trap in disguise. On one hand, the child desperately misses her loved one and wants to know that she is missed too. On the other hand, it’s also an attempt to try and gain some comfort or understanding about the altered existence of the deceased.
The best way to respond to this question is to create a hybrid of explanations: “I’m sure she misses being able to hold you tight and kiss you on the cheek, and I’m sure she misses being able to walk you to school and tuck you into bed at night. I have no doubt she misses those things dearly, since she loved you very much. But I’m also pretty sure that wherever she’s at right now, she’s closer to each of us than we could ever imagine. She might be looking in on us from heaven right now, wishing she could just reach out and give you a hug and tell you that everything is alright.”
This way you’re giving validation to the child’s need to know that Mommy misses her (in the same way she misses and longs for Mommy) by talking about the physical things they are no longer able to do together. But you’re doing this without throwing a puzzling riddle into the other ideas a child commonly receives about heaven or spirit or loved ones always being close to us. It’s a way to bridge the understanding between the physical and psychological representations of death.