i’m new to dm’ing a game and currently my players are trapped inside a cave. One player at the end of the session asked if she could eldritch blast the rubble trapping them to remove it because she could do it in bg3 and I’m wondering if there’s anything against it? or is this something I should decide as a dm https://100001****/ https://1921681254.mx/ ?

There are two angles to this:

What do the rules say?

Eldritch blast says:

A beam of crackling energy streaks toward a creature within range.

This means eldritch blast cannot be used to target objects. Compare this to fire bolt, which can target both.

What makes sense at your table?

You're the DM, you can just decide that eldritch blast can be used in this way.

The Dungeon Masters Guide has further guidance for how to handle something like this:

When characters need to saw through ropes, shatter a window, or smash a vampire’s coffin, the only hard and fast rule is this: given enough time and the right tools, characters can destroy any destructible object. Use common sense when determining a character’s success at damaging an object. Can a fighter cut through a section of a stone wall with a sword? No, the sword is likely to break before the wall does.

The DMG has further information about the AC of stone (17) and how many hitpoints a discrete stone object would have. Note that is says discrete objects. Without getting too much into the weeds on what this means, let's just say the rules assume that bigger objects take comparatively more time to destroy than smaller objects.

So, if you decide that a player is able to roll damage against a wall, my advice would be: make it take some amount of time. It might even be faster than digging out the stone with pickaxes, but it's probably not going to be a lot faster.

"Okay, you set your sights on destroying this wall. Repeatedly casting eldritch blast to chip away on it will take you an hour."

If there is no time pressure and no enemies nearby, no problem, just fast forward. But if they're in a hurry and enemies can potentially hear the hammering of hundreds of eldritch blasts being thrown against the wall, it now becomes an interesting decision.

Eldritch Blast targets creature, but the DM can always rule differently.

Targets: A spell's description tells you whether the spell targets creatures, objects, or a point of origin for an area of effect (described below).

As the others have said RAW no but up to your DM.

My DM allowed me to use Produce Flame to target an object that had oil splashed on it to set it on fire. Even though that spell also can’t target objects. 

Sometimes the rule of cool or common sense seems the best call. I don’t see why most pew pew spells can’t target an object  but I’m sure it’s maybe balance issue? I don’t see a down side as long as it’s an object that isn’t worn or carried. But maybe I’m missing something. 

During one of our adventures, while fighting an evil priestess and some of her acolytes in a very old tower, the woman, in a final act of desperation and madness, cast a 5th-level fireball in a room no more than 30 feet radius.

RAW, fireball doesn't damage objects, only ignites them, but that fireball dealt a lot of damage (10d6). The DMG set an amount of HP for the walls and this story ends with the walls, roof and floor crumbling, damaging again the party. Two of my players dropped to 0 HP.

Later, the DMG realized the fireball in 3e has the following description, so rule of cool or not, it was funny and deadly.

A fireball spell is a burst of flame [...] Unattended objects also take this damage. The explosion creates almost no pressure. [...] The fireball sets fire to combustibles and damages objects in the area. [...] If the damage caused to an interposing barrier shatters or breaks through it, the fireball may continue beyond the barrier if the area permits; otherwise it stops at the barrier just as any other spell effect does.