It looks as if you are flying Delta. You can go online to your reservations and request a wheelchair. When you check in, they can see that you need a wheelchair and order one for you. You can also order one from the check-in counter.
You will not be able to be eligible for exit row seating regardless of whether or not you order a wheelchair if your mother has any obvious signs of disability like a cast on her foot or a limp or a cane.
It is seriously not a good idea for your mother to be in these seats. Able-bodied people should occupy them. If there was an emergency you would not want your mother to be responsible for the inability of passengers to exit as quickly as possible. I would never even think of sitting in one of those seats.
If there are no visible signs of disability, and you order a wheelchair it is likely that the flight attendant will ask you to move, and she should do that because it is an unsafe situation.
So if you have to make a decision between using a wheelchair to move around in the airport, or having a exit row seat, I would always opt for a wheelchair. It seems like most of my flights this winter have not arrived on time, making my connection time very quick. Without my wheelchair I would have certainly missed my last plane changes in Orlando and Detroit.
I find the pain of walking to be much more severe than the slight advantage of a bit of extra room in the exit row, and making a connecting flight is generally much more important to me than a bit of extra legroom.
The best seat for people who need extra legroom is the bulkhead seat. Sometimes I have called my airline and asked them to release a bulkhead seat. Normally these are assigned by the gate agent, but if you have a valid request (I had just had my hip replaced) they will often just assign you to bulkhead seats in advance. The only danger is that you can be bumped from those seats if someone is on the plane with a service dog. That has never happened to me, but when they give me bulk head seats in advance they always warn me about that contingency.
My experience with Delta is that if I am not successful with the first phone call I just call until I get someone who will do what I want them to do, so if at first you do not get bulkhead seats, try again.
I would order a wheelchair and call Delta and ask them to pre-assign you and your mother to bulkhead seating.