A bag with her medical supplies can be carried IN ADDITION TO the normal carry-on allowance. If she is questioned about the extra bag (total of three) she should say that it contains medical supplies as permitted by the Air-Carrier Access Act.

Both the laptop bag and purse count as separate items. If she carries both then she'll have to check her roll-a-board. If she wants to carry it all on she'll have to combine the laptop bag, purse, and roll-a-board into two bags.