Assuming all 3 of them were required to sign to release title and a check was made out to all 3 of them, then YES all 3 of them need to report their 1/3 of the proceeds. My expectation would be that all 3 of them qualify for exclusion and will have no net gain to report on the sale of their personal residence. 

Sold at a profit?  That's one to send  Ripley, unless it had been a rental and fully depreciated before they moved in.  

If they all 3 qualify for the exclusion what do I do? There was no gain with the exclusion. 

I just am wondering if the dad has to get off as a dependent

If you are SURE there is no 1099-S and it will be fully excluded, you don't need to report it at all for Federal income tax purposes.  But perhaps the State or other things could be different.

Or you can report the sale (Home Sale Worksheet), where you enter the Basis, the Sale Price and then exclude the gain.

"I just am wondering if the dad has to get off as a dependent"

Why?

"There was no gain with the exclusion"

No gain? Or no taxable gain?

As Bob noted, it is rare to sell a mobile home at a gain.

@sjrcpa Maybe he's worried about the Dad not qualifying as a dependent because his income would be too high.  And maybe this is a situation where the park owner paid off the owners to haul the scrap metal away so some real homes could be built on the property.