In fact! I'm going to play this military analogy to it's fullest extent.
The Kissuisō is not an inn. It's a mighty fortress. The employees are actually platoons of soldiers tasked with defending it. The Grandmother is the general, but hse has been knocked out of commission. The customers are not customers at all, but a
Panzergrenadier division equipped with tanks and self propelled guns! In order to prevent these mechanized barbarians from ravaging and annihilating the mighty Kissuiso fortress, the defenders must sally forth to battle to hold them off.
But the Kissuiso fortress defenders are undermanned. And their heavy weapons platoon armed with Bazooka's and Machine guns (Ren) is currently combat ineffective. Without heavy weapons, Mighty fortress Kissuiso will be overun, burned to the ground, and all it's defenders bayoneted and machine gunned to death. Nazis know no concept of mercy.
The only way to prevent disaster (or at least leaving the Fortress wrecked), is for them to link up with Tohru's unit, their second heavy weapons platoon. But they can't make radio comms with this unit, nor do they know exactly where it is. The only way to get it to reinforce the fortress, is to send a platoon out on recon to find them and get them to come back.
Ohana is actually a platoon of light infantry. Dedicated, but Lacking in heavy weapons. They're certainly useful point defense and stop gap for the defenders, but they as useful as the heavier armed platoons in this stand up war of attrition. Sending the Ohana platoon to link up with the Tohru platoon isn't necessarily a bad idea. Since they're dedicated enough that you could reasonably expect them to find the lost heavy weapons platoon, and bring them back to defend the Fort. The Ohana platoon might be less combat effective when it gets back, and the fort will be more undermanned while they're gone. But they'll be in a better position if the recon platoon can bring back reinforcements.
There are other platoons you could afford to send, but they're not as good options. Jiromaru platoon is certainly just a bunch of worthless barely armed conscripts. But it's questionable if they'd be able to retrieve the Tohru platoon (or even convince them that they should abandon their current mission to come back and defend the fort). The Takako platoon suffer a similar problem, in that they're an overpaid PMC platoon, and it's unlikely that Tohru platoon would abandon their current mission based on their word.
Now you COULD send the Minchi platoon. They're arguably only somewhat helpful to the currently incapacitated Ren heavy weapons platoon and the Ohana platoon could conceivably help them out (they lack heavy weapons, but they do have some training on them). But then there's the question if a meek, passive aggressive platoon like the Minchi platoon really has what it takes to go on force recon and retrieve the Tohru platoon.