Is it safe to have a manhole directly under my mobile home?

Manhole was there before the mobile home... How can they access the manhole if the mobile home was placed over it... I do not believe mobile home legally can be put there.

There are easements for buried utilities including sewers, and structures should NOT be placed on top of them. In the USA anyway.

What if the buried utility had to be excavated for repair or replacement?

Are you sure it is a manhole? Most of them are in the street. Show us a picture. How big is this "manhole".

I have several actual Manholes in my back yard... so its possible.

All of the ones I have seen in yards are for sewer access. In many GA locations, they are in flood plains, elevated above 50 or 100 yr. floods, some of them 4' above ground.