${\mathrm{H}}_2{\mathrm{O}}_2$ is:

Hydrogen peroxide acts as both a reducing and an oxidising agent.

Hydrogen peroxide's oxygen, has a -1-oxidation state, is converted to ${\mathrm{H}}_2\mathrm{O}$ when ${\mathrm{H}}_2{\mathrm{O}}_2$  acts as an oxidizing agent it has -2 oxidation state.

As a result, in alkaline solution, hydrogen peroxide functions both as an oxidising and reducing agent towards certain first-row transition metal ions.

Hence, correct option is B.