If you have a lease the new owner has to honor it.
If you are on a month to month and they wish to have your unit vacant and you have been in the property a year or more they will have to give you a 60 day notice. If you have been in less than a year they only have to give you 30 days.
If you are on a lease and they want the unit vacant they will have to negotiate with you and you could definitely ask for and get moving expenses.
Another possibility is that the new owner may want to keep you as a tenant.