I believe they are 2 different women. (notice the white edging on shorts of the one next to the boy who died. That white edging is not on the shorts on the woman with the Tufts Sweatshirt in the street.) I believe she (the one next to Martin) is the boys mother. There was Martin, his dad (who is a runner but did not run this yr), his mother, his little sister and his older brother all together. Older brother was not wounded. Little sister lost leg, mom had head injury, dad scrap metal injuries.
Three members of the Tufts women’s Lacrosse team were injured in the 2nd blast (very possibly the 3 in the picture with matching nike shoes.) The striped socks are part of their uniform. From what I’m reading they were treated and released so the three girls with the bomb placed right behind their feet must have thankfully moved on from their position in the first picture.