Okay, so at three am, it sounds like there was someone beating on the wall...wonder if it was the beating that killed her, or if that was someone trying to revive her?
But that definitely blows the mother's timeline out of the water.
Beating wall sound at 3 am (roughly)
Mother says she moved her to couch at 5:30
Reported missing at almost 7 am.
I tend to look for the truth in the lie, 5;30 is probably when she was moved, either she was already dead or dying and mother used the sleeping on the couch excuse to explain why there is urine or feces on the couch. It they find her in time, COD is probably going to be blunt force trauma.
What is going on lately? For Pete's sake, call CPS on yourself, if it gets that bad, it's better than a murder rap.