In retrospect, the laminate flooring should have been continued to abut the tile and door threshold. If you're doing this yourself, and still have some material left, the transitions in A and B could be bridged with another piece of laminate, ripped down to the proper width. C is more difficult, because the boards are cut off and perpendicular to the tile, and you can't lengthen the boards retroactively to meet the tile (but keep that in mind for your next job). If this isn't possible, then do what stonetech said, and get a couple reducer strips.

I did both. I was taught by an installer how to flush cut the flooring to butt up against the tile, which did have an edge strip, with a 1/16th (I think, it’s been almost 2 years) gap and silicone caulk. I hated it because the flooring is matte and I couldn’t find a caulk that wasn’t shiny so it left an obvious shiny line between the tile and the laminate flooring. I replaced it with a transition strip. I do remember messing with the strip to making it as flush as possible between the two different floorings, I think we had to modify the metal piece inside or route one side deeper. keep in mind all of this was DIY and with proper planning by a pro installer the different floor levels are taken into account. I changed my mind and decided to tile the powder room when the flooring was already in. Also, in this scenario the ends are supposed to be sealed and caulked beneath the transition strip in a powder room application, even if it isn’t “wet,” like with a shower or bathtub. That was so deep in the specifications for the flooring we almost missed it. I did not use a transition strip by the front door. I intended to, just to be cautious since we spanned a greater distance, but I hated how the strip looked. Next to the threshold the caulk is invisible, even though it’s shiny. We were pressed on time and budget because it was a new home without any closet shelves, garage storage, or landscaping. The idea of replacing the carpet that was falling apart (after less than a year) with more of the same carpet by the builder was discouraging to me, so we really couldn’t do anything differently. But in a more predictable world, if I could have wrangled a couple thousand more, I have done a simple, not engineered, hardwood and installed it ourselves. The laminate has not had any issues at all as far as buckling or drifting. It’s on our main floor and the only place with an issue is where my kids drop ice cubes on the floor in the same spot and don’t pick them up. There isn’t any swelling or peeling but there is a thin line where you can see the composite is a different color. This is not in an area with a long span. The LVP with equivalent numbers of pieces were 2-3 times as expensive.

I probably wouldn't use one. Unless the ridge is big enough to trip over.

I would cut the transition piece and then install the shoemoulding. Be careful, so you get transition, exactly right, so there wont be a gap, when you put it back down.