Is it legal for my mother-in law to sell my husbands truck?

my husband and i have had alot of problems with his mother.. she is crazy! when i first met the women she was poor and lived in a dump.. she is a drug addict and an alcoholic, not to mention all the prescription drugs she is on. Anyhow about a year after my husband and i were together his rich grandmother died.. his mother said she didnt leave a will so she told us she got all of it.. i told my husband to check into it and make sure, but he never did.. well his mother got 1.5 million dollars. we were getting along with her pretty well before and after his grandma died.. so about 3 months after she died she gave us 25 Thousand to pay off bills and buy a new truck.. we were very grateful. then things got crazy.. my husband and i found out we were gonna have a baby and told her.. she flipped out saying it was gonna ruin her sons life and put us in debt and she isnt helping out at all.. then she started calling me a whore and trying to turn my husband against me… he was hurt that his mother couldn’t just be happy for us, so we stopped talking to her.. i was pretty pissed off that she would call me a whore when she didnt know me, so i wrote her a smart ass comment saying i guess we will see what color the baby is.. i said she is being crazy and stupid and i told her there are far more important things in life then money.. well we didnt talk to her until i was about 7 months and then she sent money in the mail saying she was helping her son.. not me or the unborn child.. he never wrote her or called her and she freaked out. she said unless my husband was in the hospital or dead never to contact her.. and we didnt.. well about 2 weeks after our daughter was born she called and left him a nasty message saying how rude we were to not call and say when the baby was born.. a week later she wrote and asked for pictures.. so i guess we started getting along again and she bought alot of stuff for our daughter.. we went to California to visit and she flipped out once again because i went to see my mother for 2 days longer then i went to see her.. well she again wrote us and told us never to talk to her again.. she wrote tons of e-mails saying i was a bitch for keeping her from her son, she threatened us that we owed her all the money she spent on us.. and so on and so forth,, we didn’t talk to her for 8 more months..well my husband joined the military and after he finished AIT we got stationed in NY, we were behind in bills and didnt have the money upfront to pay for the move.. so my husband asked his mother to loan him 2 thousand and he said he would pay her back when he got his tax return.. well all was well for about 4 weeks we talked to her everyday.. she mentioned that if we bought her a ticket to come see us then we would call the loan even.. we bought her a ticket and she decided not to come.. i was pissed because i planed alot of stuff.. so i ignored her calls for about 3 days she again for the umpteenth time turned it into a pitty party and told us not to speek to her! well a week after that she wrote an e-mail saying she wanted monthly payments for the 2000 we borrowed.. well my husband is deploying in October and he wrote her no.. it we werent gonna pay monthly payments.. he wrote her that he would pay it in full when we got our tax return.. well it was quiet for alittle while till she found out i was going home for the holidays after my husband gets deployed! she wrote us and demanded us to pay her back.. that if i had enough money to go home that we had enough money to pay her.. i got pissed once again and wrote her that it was none of her business how we spend our money, and that she would be paid back in full from our tax return.. well before my husband moved away from california he had a 1970 Chevy that he was fixing up.. well this whole time it has been sitting at his mothers house.. well yesterday she called and said she was selling everything that was his at her house including his truck! she never gave us warning to go get it!! is what she is doing legal? can she really take his property and sell it for the loan.. the truck is worth way more then 2000 and to my husband it is priceless he loves that truck!.. my mother lives near her is it possible for us to give permission to my mother to get his truck?.. the deal was we would pay her back when the tax return came.. thats not for about 4 months!! what do we do??