Sorry but none of the above replies are even worth investigating.
20″ stand over is not really possible for a traditional (mens style) 26″ wheeled double triangle hardtail frame. (a 14″ frames’ standover will be around 26-28″)
The only options I can think of to find anything that low with 26″ wheels would be a trials frame where the seat-tube might not even work for anything other than stood up riding or to go with a traditional ladies style frame with a dropped top tube or none at all.
or
The top one is a Giant Revel, a neighbour has the mens version and it’s not a bad (cheaper) bike for the money