hacker harassing me and my friends need help

The correct thing is for her to block, and report, when she is on partychat with friends, leave the group with an invitation only. Good luck!

you can also ask your friend to set the party invites to invite only and/or appear offline to stop the person harrassing them. Just follow the advice on this to your friend.

Your friend can try the following:

She needs to bring up the profile of the person harassing her, and block as well as mute the profile. This will prevent that profile from talking and messaging her, as well as seeing her being online.

However, if she is in a party with others, make sure that the party is set to be invite only. Either she needs to ask the creator of the party to make that setting, or she herself should start the party, set it to a private invite only party, and then add
the party members she wishes to talk to.

Be aware however, that a friend participating in that party, could still invite that harassing person. But she would be unable to hear him, as she muted and blocked that person.

As for game lobbies: Unless the game allows private only lobbies, there is no way to keep that person out of the game, but Xbox Live will TRY to keep blocked persons out of the matchmaking process, if possible. She needs to make sure that the harassing person
is then also muted in the in-game chat.

If the person uses multiple accounts to get around the block and mute setting, she could temporarily set her account to be contacted by "Friends Only" in
her account's online and privacy settings.

That way, only persons that are on her friend list can contact her.

And whenever she gets a harassing message, she should report that message through the console's reporting feature. The console's involved will then collect data and evidence, and send that in with the report to the Xbox Live Policy Enforcement Team. They
can then issue suspensions or permanent bans for the harassing person.

The enforcement team will look into since you have reported him, it will take time though.

You need to report, block, and file a complaint on the person. It is best to just ignore them these people just want attention. For more information on enforcement please visit Enforcement