For lower tiers Mercy is a very sufficient counter to Widowmaker because she helps empower other long range heroes to gain kill power against her to lower their TTK while removing herself as a target on top of reversing the kills Widow tries from range.
Widowmaker is the worst hero to camp a kill unless she killed someone in open space which is usually rare. Brigitte is okay option because shield lets her close distance with a divey team offering repair pack and shield allows you to block damage to close distance or peak around corners.
Kiriko is sitll one of the smallest heroes so that with the larger projectile size and no drop off she can provide some pin point burst that other supports can’t do. These are all very safe options and generally low skill too unlike Lucio.