3 months is nothing. A diesel can sit for 10 years and fuel not go bad, except if moisture gets inside the fuel tank to grow black slime. Boaters know about that, since damp on the coast and some engines are rarely used (sailboats). If slimed, you can pour in biocide to salvage the fuel (any truck stop).

If you do replace the rubber fuel hoses, best to use Goodyear "Barricade" brand, or equiv., which has a Viton liner and stamped "for bio-diesel". If like my 1984 300D, the return is a special swelled hose termed "cigarette". I thought it had swelled when I first saw one, but it's meant to be. Something about damping fuel system pulses, but probably not noticed if you use regular straight hose there. The max pressure on the rubber hoses is 12 psig, from the pressure relief on the injection pump inlet. It should decay quickly after shutdown, at least I've never seen a squirt when opening a hose after the Lift Pump.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans