Does she have any legal claim to an inheritance since she no longer bears his name?

Yes, the name change has no effect, unless he specified to the contrary in his will or other document.

A name change doesn't alter the relationship. If your aunt was adopted, she bears the same relationship as if she were Grandpa's natural child.

Yes, she can still inherit from him, because she is still his adopted daughter, regardless of her name change. (Similarly, she could have gotten married and taken her husband's name without giving up her inheritance). Whether she as any legal claim to an inheritance depends on what your grandfather's will or trust says.

Your question is difficult to answer because it raises more questions. Presumably you are asking if your aunt has a claim to an inheritance from your grandfather's estate. The answer depends on a number of things. Did your grandfather have a will, trust, or other estate plan in place at the time he died? If so, assuming the will or estate plan is valid, then that document should control how his estate is distributed. If the answer is no, then your aunt's right to inherit would depend upon whether your grandfather left a surviving spouse, how many other children of his survived, etc. But generally speaking, adopted children have the same status as biological children and changing last names, particularly for women, has no bearing on whether someone is or is not considered the heir of a decedent. You should consult an experienced probate attorney in your area.

The crucial fact is the adoption not the change of name. Her adoption makes her the child and one of the heirs of the grandfather unless his estate documents specifically state that she is not to inherit anything from him.