Can I be sued successfully by a company in Maryland if I now reside in Indiana?

Can you be sued successfully in a state other then where you reside?  Yes.  It happens every day.  Assuming that you are eventually served, the question would be whether you had sufficient contacts with Maryland so that its courts could exercise jurisdiciton over you without violating the Constitution.  If you previously worked in Maryland, and this suit arises out of your employment relationship with a Maryland business and/or work you performed in Maryland for that business, the answer is probably yes (also, if the suit arises from a contract between you and the Maryland company, it is very possible that you agreed in the contract that any suit relating to it could be brought in Maryland.)  You could move to dismiss on the basis of an inconvenient forum, but that would be difficult to win unless all the witnesses reside in Indiana.  You may be able to defend the suit without personally having to appear in Court, just sending your attorney, but the likelihood is that you will have to appear in Maryland at least once, probably more.