The first time I ever attempted a rescue mission in KSP, I ended up stranding 5 different kerbals in various orbita nearby trying to get the first one, and of course every one was a bigger and more complicated craft trying to save as many kerbals as possible. Eventually I just gave up and put a giant cross memorial in orbit, part as a reference to Neon Genesis Evangelion, and part as a memorial to the like 6 kerbals I left stranded in space.
Kerbals don't need food or water and can live forever on a limited air supply. I once rescued a kerbal who got stuck around their equivalent of Venus for multiple years. So it's all fine, they'll patiently wait...