Can a person who lives out of State be an executor of a will in Indiana?
There's no such thing as "an executor of a will." A person may be nominated in a will to serve as executor of an estate. That person will become executor of the estate upon application to the court and a court order. I assume this is what you're asking about.
Section 29-1-10-1(c) of the Indiana Code provides that a non-resident may serve as executor (personal representative) if there is a resident who will serve as co-personal representative and posting a surety bond.
I was told that in Indiana that the executor of an estate MUST also be a resident of the State.
Told by whom? What did the lawyer who wrote your wills say when you made inquiry about this?
Would it be better to have her and my grandson who lives locally be co-executors?
Other than their status as resident/nonresident of Indiana, we know nothing about your daughter and grandson and, as such, cannot intelligently opine about which would be a better choice. However, as noted above, since a nonresident cannot serve as the sole personal representative of an estate, if you want your daughter to be personal representative, then your grandson (or some other resident) would have to be co-personal representative. Also keep in mind that the cost of the surety bond needed by the nonresident personal representative will be an expense that the estate will have to pay.
The information I have found says that a non-resident can be executor if there is also an in-state co-executor. Alternatively, a non-resident can be the sole executor if they post a bond and file a notice to accept the appointment and to appoint an agent (in-state) to accept legal documents, papers, etc.
As I read the statutes, these are not alternatives (i.e., the requirements are conjunctive, not disjunctive).