I've taken the train many times when my dad was no longer up to driving to/from the airport. The cost of taking the train from Metropark to EWR is much lower than Uber. Most of the day, there are trains leaving Metropark that will stop at the Newark airport rail station every 20-30 minutes. One way fare for anyone 12 and up is $14.50. Children four and under are free, kids 5-11 pay half price (normal fare $11 one way) when riding with another paying passenger. The monorail was never crowded in my experience if you are flying midday. I see Metropark charges $12 per day for parking and you can stay up to 21 days.
So for a 14 day trip: parking at Metropark = $12 * 14 = 168. Two one-way tickets for the train = $29. Total cost $197. If you park at EWR, that's $44 * 14 = $616. I'd take the train and save over $400.
Uber to/from the airport is likely cheaper than the total cost including parking, if you must leave a car at Metropark.