  In this work, we study the silicate dust content in the disk of one of the
youngest eruptive stars, V900 Mon, at the highest angular resolution probing
down to the inner 10 au of said disk, and study the historical evolution of the
system traced in part by a newly discovered emission clump. We performed
high-angular resolution mid-infrared interferometric observations of V900 Mon
with MATISSE/VLTI with a spatial coverage ranging from 38-m to 130-m baselines,
and compared them to archival MIDI/VLTI data. We also mined and re-analyzed
archival optical and infrared photometry of the star to study its long-term
evolution since its eruption in the 1990s. We complemented our findings with
integral field spectroscopy data from MUSE/VLT. The MATISSE/VLTI data suggest a
radial variation of the silicate feature in the dusty disk, whereby at large
spatial scales ($\geq10$ au) the protostellar disk's emission is dominated by
large-sized ($\geq1\,\mu m$) silicate grains, while at smaller spatial scales
and closer to the star ($\leq5$ au), silicate emission is absent suggesting
self-shielding. We propose that the self-shielding may be the result of small
dust grains at the base of the collimated CO outflow previously detected by
ALMA. A newly discovered knot in the MUSE/VLT data, located at a projected
distance approximately 27,000 au from the star, is co-aligned with the
molecular gas outflow at a P.A. of $250^o$ ($\pm5^o$) consistent with the
position angle and inclination of the disk. The knot is seen in emission in
H$\alpha$, [N II], and the [S II] doublet and its kinematic age is about 5150
years. This ejected material could originate from a previous eruption.
