A combination of 1N4007 diodes in place of M7
From the look of it, a diode marked M7 is just a 1N400x in surface-mount packaging. So a single 1N4007 would be theoretically identical (as long as you aren't using the diode in some breakdown mode), as the only thing that differs in the 1N400x series is reverse blocking voltage and the 1N4007 has the highest out of those.