Answer:
He visited the cabin in the mountains every winter with his brother, who is now a doctor.
Step-by-step explanation:
He visited the cabin located in the mountains every winter of
his life with his brother, who is now a doctor of medicine.
located: you don't necessarily need this because if we state where it is, then we are stating where it is located
of his life: unless of course this was purely fiction and was describing some sort of pre, or post-life situation then it has to be during his lifetime, it is unnecessary
of medicine: while this could be an important thing to distinguish, in this sentence it seems unnecessary and can be taken out
*These of course are the ones that seem most redundant and wordy to me, there could be others, or some of the ones I pointed out might be important, but I hope this helps!*