Barthen backs away as far as the cramped space allows, holding his hands up. "Believe me, sir, I wholeheartedly agree. I consider Gundren a personal friend, though I know dwarves are slow to reciprocate. I was excited when he said he and his brothers had a lead for rediscovering the mine of the Phandelver's Pact."
The Phandelver's Pact is a story known to Kovoir: More than five hundred years ago, clans of dwarves and gnomes made an agreement, known as the Phandelver's Pact, to share a mine rich in both material wealth and magical power in a wondrous cavern known as Wave Echo Cave. Humans allied themselves with the dwarves and gnomes as well, building the prosperous city of Phandalin, whose ruins are now the foundation of the small miner's town Phandalin. But disaster struck when a horde of orcs swept in from the North and attacked Wave Echo Cave to seize it. Mercenary wizards supporting the orcs and mages of the Pact clashed over it, and the location of Wave Echo Cavern was lost in the destruction and cave-ins that followed and decimated both sides.
In the present, Barthen goes on to describe the situation in Phandalin: "There is basically no authority or lord here to chase off the brigands - it's a very free place, but one without protection. And ever since the Redbrands moved in, most of the townsfolk are preoccupied with the town itself. They're bullies and extortionists, and openly flout the townmaster's authority." He shakes his head. "If you're of a mind to find Gundren, I will support you to the best of my ability. I have here anything an expedition might need, short of weapons or sorcery. And I shall introduce you to another fellow Gundren hired. He should be able and willing to help."
Barthen's Provisions stocks basically any and all standard equipment that isn't a weapon or armor and doesn't cost more than 25 gold pieces.
Barthen is definitely in favor of you investigating Gundren's disappearance, and will call for Kuroimaken's character to join up - which leads us to a decision you have to make now. If you want to set off immediately, you have the opportunity between the uneventful ride from the ambush site and your stop in town to catch enough of a break to qualify as a short rest. This means you can roll any number of your hit dice (of which you have just one at this level), plus your constitution modifier, and regain hit points equal to the result. You'll likely be investigating in the evening and at night, and may not be at full power (especially poor Pieron), but it's the most expedient option.
The alternative is to spend the night in town, counting as a long rest. This will basically replenish your full hit points, daily class features, and spell slots, and you can set off in the morning, but represents time lost. The choice is up to you all.