Medicare will only pay for either a wheelchair or a walker but not both at the same time.
So the person will need either have the wheelchair or the walker paid for by medicare and it must be medically necessary and prescribed by a doctor for the wheelchair or walker to be paid for by Medicare.
I would have the Medicare pay for the wheelchair because wheelchairs are usually more expensive than a walker that you can easily buy at a pharmacy or medical supply store.
My Grandma had Medicare pay for the Wheelchair and I just bought her a Walker to use which was only $40.00 for the purchase price which was really reasonable.
So it's not very costly to purchase a medical walker so I would just purchase the medical walker myself and let medicare cover the cost of the wheelchair.