When Tree comes to find Tombs in the first loop of the new universe, his bed is empty not because he's escaped, but because he's been taken down to the OR. We then find out that Lori is the one who did so: which must have been not only how she had the opportunity to set him free in the original universe, it's also how Butler intends to frame Tombs for Lori's murder in the second - he would supposedly have killed her during his hospital escape.
One death scene for Tree has the camera linger around for a couple of seconds to show Carter and Danielle's reactions. This implies the possibility that just because Tree exits a timeline doesn't mean the timeline ceases to exist, meaning there are about 20 versions of Tree's father who had to bury their daughter and about 20 versions of the killer who got away scot-free (although the film mostly implies that the looping isn't timeline-hopping, and the reaction is just there for the lulz).
Alternatively, the loop lasts long enough for the viewer to see Danielle and Carter's reactions because, while mortally injured, Tree wasn't actually dead yet, and (if she was unlucky) still conscious and suffering.