So why didn't Mama try to take Victoria and Lily into the lake with her during the five years she was alone with them?
Ooooh! I have a theory! She had to relive the "people chasing me while I carry my baby" moment?
This troper figured it was a last resort. Like... she realized they were going to drift away if she didn't do something, and in her twisted mind, leaping into the lake with them was the only way they'd be together. Sort of like what went through her mind during her life. "They won't let us be together when we're/you're alive, so we'll both be dead together." And this time it worked out and they died together, and so she could rest in peace. Or something.
Being a ghost, a lingering emotion that must be set at ease, she could have also been trapped in a loop that forced her to reenact her last acts on Earth when faced with the same threat (someone trying to take her kids away.) There's also how she first tried to merely spirit them away from the house in the middle of the night, but Victoria simply refused and Lily didn't make it very far (and worse, Lily started developing some small affection for Annabel when the latter brought her in from the cold.) So Mama might have realized that not only was someone else taking the girls away, but she was also losing the girls to them. Like the troper above says, taking them to the cliff could have been her last resort.
So, uh, why'd Mama possess Aunt Jean? She seemed fully capable of carrying the girls wherever she wanted without possessing someone.
Easier to get through toll booths? (No nevermind, Possessed!Jean was scarier than Mama...)
Well, she IS a ghost. While she can carry people off the ground, maybe she couldn't carry them for the dozens (if not hundreds) of miles from the house back to the cabin. And, during their games with the blanket and during the climax, we see that if the girls resist they can exert some force against her (so if Victoria didn't want to go, Mama would've had a lot more trouble taking her.) There's also how Mama, for all her ferocity, prefers to stay in hiding and watch from the shadows unless absolutely necessary (probably because she remembers the mob chasing her to her death) so carrying them herself for such a long distance, while risking being spotted, with at least one girl struggling, might have been a risk she wasn't willing to take. Personally, I believe that Lily's "escape attempt" was Mama's first try at getting them back to the cabin, but for whatever reason, Lily could only make it to the far end of the backyard. So, Mama realized she needed a physical presence who would have an easier time taking them back home.
This troper got the impression that, whatever Edith's reason for luring the girls out that night—be it to try to take them home or to play—she got distracted by the doctor showing up at the cabin. Maybe it wasn't so much that Lily couldn't make it past the back yard as that no one was guiding her. Immediately when she comes outside, she calls for Edith and sounds confused when she does not appear, wandering off but ultimately not very far.
What did Lucas find in the cabin?
Possibly Dreyfuss's corpse.
Where did Dreyfuss's corpse go?
Mama probably hid it.
These kids have massive balls. Mama would've scared the shit out of me at that age.
Well, they grew up with her. That just seemed normal for them. But yes, those kids were awesome.
Where'd the cherries come from? Does Mama create them? She couldn't have picked them, since it was the middle of winter. And what else were the girls eating besides cherries, to get protein? Bugs?
Well, the drawings at the beginning of the movies showed the children eating dead animals like a dog would. Perhaps she fed them raw racoon meat or something?
In the scene where the girls visit Lucas at the hospital, Lily is shown eating moths. So yes, it's pretty likely that they also ate bugs.
What was Dr. Dreyfuss planning to do when he went to the cabin? He seemed to have realized that Edith's dead baby was the key to dealing with her, but he didn't bring it with him! Was he planning to reason with the murderous ghost?
He had a camera with him, so it looked like went to get proof. He left during the daytime but only arrived at night and decided to go in alone.
What was special about the cabin to begin with? Who put it there and why? Did Mama have anything to do with it or was it just coincidence?
It's just the house nearest where Mama died. She my have killed the original inhabitants.
Actually maybe it was hers at one point.
How are Lucas and Annabel going to explain losing Lilly to Child Services?
A feral child being unable to adjust and running away isn't a hard story to swallow. It won't entirely remove the suspicion, but considering there's no evidence to support them murdering her the case will likely be dropped.
When Mama was chasing Victoria and Lilly up the stairs, why did Lilly run?
From what Victoria said, Mama was angry and who doesn't fear their mother when she is angry? Also, she was mostly going by Victoria's behavior.
She might also have thought Mama was just playing tag. In an earlier scene, we see Mama playing with one of the girls. They're playing tug-o-war with a blanket — and Mama suddenly lets go, allowing the girl to slam against a dresser. Maybe this isn't the first time Mama's gotten a little rowdy?