We're a family of 4 with 2 boys who will be 6 and 4 years old by next late March 2018, which is the target date for our trip with my mother in tow as well.

wants
-non stop flight from Newark airport
-2 connecting rooms (one for 4 of us/another for mom) or 2 bedroom suite 2 bathrooms
-GREAT kids club
-good food
-budget $6,500-8000K
-sandy beach

anyone???

I absolutely can't help.
No idea what flights go from Newark. None.
You don't mention the duration of your stay so budget is useless.
You don't say if budget includes flight tickets.
You want all inclusive ?

My rec would be to go to Mexico.

If you can fly from EWR, you can fly from JFK and perhaps give yourselves more options.

Why don't you figure out which countries/islands you can get to from these airports then check out the offerings. Your budget does not seem alot if it is to cover 5 people/2 rooms for a week, all inclusive hotel and flights.

Least Expensive
Dominican Republic
Mexico

More Expensive
Barbados
Antigua
St Lucia
Jamaica
USVI
etc

Aruba - no need for all inclusive hotels
St Martin - no need for AI

Ok, truth is with one or two minor exceptions you'll find a "sandy beach" on just about every island so that doesn't factor into your decision making process.

Also, from I agree with with Odin, if you are willing to fly from any of the NYC airports there are scores of islands you can reach non-stop and even if you must only use EWR you'll still have lots of destinations to choose from so here again the "non-stop flight" requirement isn't going to greatly affect your final destination.

Beaches Resort on Providenciales in the Turks & Caicos is perhaps the number 1 "family oriented All inclusive Resort" in the Caribbean but it is probably going to be outside your $8,000 budget (and that's even assuming your budget doesn't include airfare).

In order for us to be of real help you have to clarify if your budget includes airfare and food costs. If food, are you looking for an All Inclusive Resort?

Does your $8,000 include the additional cost of the Children's Program or are you expecting to have that as part of your room rate?

Note: When you give a budget spread of $1,500 the contributors here will most likely focus on the higher end of your range while you'll be thinking toward the lower end so be prepared to spend more rather than less.

Now, with a need for multiple bedrooms you might consider staying at a 2 or 3 bedroom "condo resort" where you'll have separate bedrooms for you and spouse, your mother and one for the kids. In addition you'll have a full kitchen and dining area so you can prepare breakfasts and lunches (to save on food costs) and then go out for dinners (or "dine in"). There are lots of beachfront "condo resorts" that are perfect for families on Grand Cayman, the aforementioned Provo, in the Dominican Republic and on St. Thomas - all of which you can reach non-stop from either EWR or JFK.

Good luck choosing your spot.

i'm no expert on family vacations but i would go to a website like cheapcarribean dot com and put in some dates and some islands and see what you can find (it has filters for where you are leaving from, number of adults, number of kids, number of rooms)

What you need to clarify is whether the budget outlined includes airfare. For 5 of you typically the airfare in March will be min $500pp - $800pp out of Newark. If the budget includes airfare then I agree you should consider suze's recommendation above. Also sign up for Travelzoo's daily/weekly email alerts.
If the budget does not include air then it will open up many more options.
Also unclear if you are looking for an AI.
My sense is that either Aruba or Grand Cayman will be good fit for you (assuming you are not interested in AI). The latter will be more expensive. Good deals can be found on Aruba.

ok, i did more research in the meantime and it seems for my budget to include all inclusive or a resort with kids club AND food to be included;

DR
Mexico

and my budget would be 8K for 5 or 6 nights WITHOUT airfare. It'll have to be 2 separate rooms though, for my own sanity from Grandma (or a 2 bedroom suite is fine)

things that kept popping up is the gran caribe resort in Cancun
and Majestic or the sister Majestic Elegance both in Punta Cana, DR that met my paremeters....but i couddn't really tell whether its adult or family resort as didn't really advertize kids club on their websites...so that's giving me pause.

help??? or am i wishing for the impossible here?? the reason i really want to keeep to 8k for room/food/activities budget cuz we're also going disney later that year in November, so need to save money for THAT trip.

someone meantioned beaches in turks and caico...i agree, its the perfect resort but we got it booked for 2019 spring break....lol its 2018 i need to figure out

I think this is the catch: most hotel resorts with kids clubs will cost too much for two adjoining rooms for your budget during high season. And the two-bedroom condo resorts with 2-bed, 2-bath suites will not have kids clubs. But many might have private babysitters, who could take the kids off your hands for a few hours.

The exception, as you noted, are the resorts in DR and Mexico. We had a great family vacation in the Playa Del Carmen/Akumal area at an all-inclusive with kids club. There are many to choose from, but make sure that the kids club has air conditioning. You might start by looking at the Iberostar resorts in the area.