I used to bring far too many spares, incl LP and HP hoses... but never needed and added unnecessary weight or just more stuff to lug around.
Over the years things I have
actually needed to replace (either for myself or others) for remote area ground based or LOB diving have been:
Mouthpiece and cable ties
Make sure it fits your reg!
Some early Scubapro or US Divers regs have smaller spigots than more modern regs, and putting a larger modern mouthpiece on an older reg will eventually leak despite a tight cable tie!
O-rings
HP hose to SPG (-003 90 Duro)
Tank K valve yoke (-014 90 Duro)
Tank K valve DIN/yoke insert (-112 90 Duro)
BC inflator hose inside QD connector (-011 70 Duro)
LP hose to second stage reg at swivel (-010 70 Duro)
LP hose to first stage reg body (-011 70 Duro)
HP hose to first stage reg body (-012 90 Duro)
BC Inflator module
I still carry an o-ring service kit and tool, but its far easier to just replace the whole module with a new one and service the other one at home after the trip
BC inflator hose Schrader valves and tool
The valve can stick or leak and the -011 o-ring is hardly ever serviced, often chopped up and leaky.
Tricky to replace this o-ring without a dental pick or suitable probe... so do it before you leave home!
SPG HP Spools
I still bring the -003 90 Duro o-rings (replaced for others many many times) but again its quicker and easier to replace the whole spool assembly... they come in three styles, the most common flanged one below: