Are the laws the same in Pennsylvania, as they are in Maryland. Could a MD lawyer draw up a new deed for my home, with my niece as second owner

Short answer, no, the laws are not the same.  The transaction you describe is a combination of estate administration (specifically, the transfer of the home from what I presume is joint names to your name alone) with a secondary objective of leaving that property to your niece upon your death.  The structure of the deed would need to comply with the laws regarding joint ownership of property where the property is located or your objective could conceivably fail after you're gone.  That being said, there are multiple ways to achieve what you are trying to do.  A Maryland attorney could certainly draft a deed but if your husband's estate has not been administered you may need a PA attorney to represent you in that aspect.  A MD attorney can do certain things in PA but appearing in court for estate administration without a PA license would be a no-no.