Is my father in law financially responsible for his spouse's funeral?

My FIL & MIL are still legally married and for the last 25 years they have lived under the same roof but there hasn't been a kind word or action between them....it really isn't a good situation. With our encouragement my FIL acquired LTC ins a few years back, has private health ins as a retired gov't employee and a great pension. My MIL never planned and the $225K set aside by her parents for her elder planning is gone; manipulated from her by my husband's sibling. That is in the past, we know, but here is our problem: MIL is in ICU (3 wks today) with C-Diff and Sepsis. There is simply no improvement and we don't know what is available financially in case of long term needs, or burial. The Dr said yesterday that she probably won't get better. I am a planner and it may sound harsh but I'd like to do the research now, just in case, rather than missing out on benefits available due to whirlwind of emotion later. When we renovated their house to save it from condemnation (hoarding) we put an apartment on upper floor for when they needed live in care and within 8 weeks we will be moving in to that apartment from our home to care for them. Her SS is enough for her food and living expenses (her husband charges her rent) but there isn't a chunk of money or any insurance policies for any large requirements. She isn't on the deed for the house and has ZERO assets. Is FIL still responsible for her burial? Please don't think that "it is the human thing for him to do", we know that and he simply doesn't agree. Thanks for your input, we need advise! Bless all of you for caring for your loved ones.