May a 90 year old man use a cane on Yom Tov in a Reshus Harabim if he is able to walk short distances without one but he wants to walk a longer distance on Yom Tov which requires the use of a cane?
Although it is pemitted to carry in the street on Yom Tov, even in a place where there is no Eruv, nonethless Chazal prohibited a preson from carrying a cane or walking stick in the street on Yom Tov, because it looks like one is not treating Yom Tov with the correct respect.
However, one who is so infirm that he cannot walk at all without a stick may walk with this stick even on Shabbos, as it becomes “part of him,” so to speak.
In the case in question, though, the man is able to walk short distances without the stick. Although at a later stage of the journey he will not be able to manage without the stick, at the first stage of the journey he could actually manage without, and so it would not be permitted to take the stick, since at the first stage of the journey he does not yet need it.
I suggest that if possible you arrange that the stick be left at a place along the journey (perhaps in someone’s house) at a which he will no longer be able to manage without it. Then he can walk the first part unaided, and when he gets to the stage where he can no longer manage without, the cane will be available for him to use for the rest of the walk.