nope i stretch it, tie a knot in it and toss to dogs to play with
I haven't got a clue how to darn or sew. (I hate anything to do with sewing and I haven't got the patience to even thread a needle!) I buy new ones, they are fairly cheap so no problem. The old ones can be chucked out or used for cleaning rags (if they are clean of course)
Neither. I wash them one last time and then they join my 'holiday' pile, to be taken on the next long-haul holiday and left in some far-flung part of the globe in a clothes bank. I've done this for several years now - it saves on washing hen you get home, and the space that the old clothes vacate in the suitcase can be re-used on the return trip for gifts and/or new clothing items
Buy new socks.