Although your parent may not use a wheelchair at home, he or she may want one for holiday parties. My mom doesn't want her walker to get in anyone's way at a crowded parties, so she plans to borrow a wheelchair for a week or so. That way she in essence brings her own chair to the party, too. Or your parent may have a safety apparatus, like rails around the toilet, in his or her bathroom at home that would not be present in Aunt Ethel's house, where the family gathers for Christmas.
To borrow short-term medical items, Google to find local nurses lending closets. If you don't see a list online of what items each has, call around and ask if that closet has the item you need. Reserve it, if possible. Also, plan to sanitize it yourself after you get it home.