If the father or grandfather are still alive, they are still her shar'i guardian, whether they play a role in her life or not. Unless of course she reaches out to them, and for an unjustifiable reason refuse to give their consent, in such a circumstance the case would be different.
However, assuming that they are still alive, she must obtain their consent.
If they have passed, for marriage to be legitimate, she does not need to seek consent, however from a social/moral perspective, she should aim at having family involved, and not pursue an ongoing relationship through a permanent marriage, and not temporary.
And Allah knows best.
In the case that her father grandfather and If we were to answer jurisprudentially, if her father and grandfather